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1995-11-08
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Archive-name: linux/howto/scsi
Last-modified: 7 Nov 1995
Version: 2.24
Copyright 1994, 1995, Drew Eckhardt
This documentation is free documentation; you can redistribute it and/or
modify it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This documentation is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this documentation; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
That said, I'd appreciate it if people would ask me <drew@PoohSticks.ORG>
if there's a newer version available before they publish it. When people
publish outdated versions, I get questions from users that are answered
in newer versions, and it reflects poorly on the publisher. I'd also prefer
that all references to free distribution sites, and possibly competing
distributions/products be left intact.
IMPORTANT :
BUG REPORTS OR OTHER REQUESTS FOR HELP WHICH FAIL TO FOLLOW THE PROCEDURES
OUTLINED IN SECTION 2 WILL BE IGNORED.
This HOWTO covers the Linux SCSI subsystem, as implemented in Linux
kernel revision 1.2.10 and newer alpha code. Earlier revisions of the
SCSI code are _unsupported_, and may differ significantly in terms of the
drivers implemented, performance, and options available.
For additional information, you may wish to join the linux-scsi mailing list
by mailing majordomo@vger.rutgers.edu with the line
subscribe linux-scsi
in the text. You can unsubscribe by sending mail to the same address and
including
unsubscribe linux-scsi
in the text.
Once you're subscribed, you can send mail to the list at
linux-scsi@vger.rutgers.edu
I'm aware that this document isn't the most user-friendly,
and that there may be inaccuracies and oversights. If
you have constructive comments on how to rectify the situation
you're free to mail me about it.
Table of contents
Section 1 Common Problems
Section 1.1 General Flakiness
Section 1.2 The kernel command line
Section 1.3 A SCSI device shows up at all possible IDs
Section 1.4 A SCSI device shows up at all possible LUNs
Section 1.5 You get sense errors when you know the
devices are error free
Section 1.6 A kernel configured with networking does
not work.
Section 1.7 Device detected, but unable to access.
Section 1.8 Sometimes the scsi subsystem locks up
completely.
Section 1.9 Configuring and building the kernel
Section 1.10 LUNS other than 0 don't work
Section 2 Reporting Bugs
Section 2.1 Capturing messages
Section 2.2 Locating the source of a panic()
Section 3 Modules
Section 3.1 General information.
Section 3.2 Status of modules under 1.2 kernels.
Section 3.3 Status of modules under 1.3 kernels.
Section 4 Hosts
Section 4.1 Supported and Unsupported Hardware
Section 4.1.1 Multiple host adapters
Section 4.2 Common Problems
Section 4.3 Adaptec 152x, 151x, Sound Blaster 16 SCSI,
SCSI Pro, Gigabyte, and other AIC
6260/6360 based products (Standard)
Section 4.4 Adaptec 154x, Adaptec 1640, AMI FastDisk VLB,
Buslogic (DTC 329x may also work),
(Standard)
Section 4.5 Adaptec 174x (Standard)
Section 4.6 Adaptec 274x, 284x (Standard), 294x (ALPHA)
Section 4.7 Allways IN2000 (ALPHA)
Section 4.8 EATA: DPT Smartcache, Smartcache Plus,
Smartcache III (Standard)
Section 4.9 Future Domain 16x0 with TMC-1800, TMC-18C30,
TMC-18C50, or TMC-36C70 chip (Standard)
Section 4.10 Generic NCR5380 / T130B (Standard)
Section 4.11 NCR53c8xx rel5 (Standard), rel10+ (ALPHA)
Section 4.12 Seagate ST0x/Future Domain TMC-8xx/TMC-9xx
(Standard)
Section 4.13 PAS16 (Standard)
Section 4.14 Trantor T128/T128F/T228 (Standard)
Section 4.15 Ultrastor 14f, 24f, 34f (Standard)
Section 4.16 Western Digital 7000 (Standard)
Section 4.17 AM53/79C974 (ALPHA)
Section 4.18 qlogic (STANDARD)
Section 5 Disks
Section 5.1 Supported and Unsupported Hardware
Section 5.2 Common Problems
Section 5.3 Device Files
Section 5.4 Partitioning
Section 5.5 Disk Geometry
Section 6 CD ROMs
Section 6.1 Supported and Unsupported Hardware
Section 6.2 Common Problems
Section 6.3 Device Files
Section 7 Tapes
Section 7.1 Supported and Unsupported Hardware
Section 7.2 Common Problems
Section 7.3 Device Files
Section 8 Generic
Section 8.1 Supported and Unsupported Hardware
Section 8.2 Common Problems
Section 8.3 Device Files
Section 9 Buyers' Guide
Section 9.1 Transfer types
Section 9.2 Scatter/gather
Section 9.3 Mailbox vs. non-mailbox
Section 9.4 Bus types
Section 9.5 Multiple devices
Section 9.6 SCSI-I, SCSI-II, FAST and WIDE options, etc.
Section 9.7 Driver feature comparison
Section 9.8 Board comparison
Section 9.9 Summary
Section 10
Section 10.1 Assignment of minor numbers.
Section 1 : Common Problems
This section lists some of the common problems that people
have. If there is not anything here that answers your questions, you
should also consult the sections for your host adapter and the devices
in that are giving you problems.
Section 1.1 : General Flakiness
If you experience random errors, the most likely causes are
cabling and termination problems.
Some products, such as those built arround the newer NCR
chips, feature digital filtering and active signal negation,
and aren't very sensitive to cabling problems.
Others, such as the Adaptec 154xC, 154xCF, and 274x, are _extremely_
sensitive and may fail with cables that work with other systems.
I reiterate : some host adapters are _extremely_ sensitive to
cabling and termination problems and therefore, cabling and
termination should be the first things checked when there are
problems.
To minimize your problems, you should use cables which
1. Claim SCSI-II compliance
2. Have a characteristic impedance of 132 ohms
3. All come from the same source to avoid impedance mismatches
4. Come from a reputable vendor such as Amphenol
Termination power should be provided by _all_ devices on
the SCSI bus, through a diode to prevent current backflow,
so that sufficient power is available at the ends of the cable
where it is needed. To prevent damage if the bus is shorted,
TERMPWR should be driven through a fuse or other current
limiting device.
If multiple devices, external cables, or FAST SCSI 2 are used,
active or forced perfect termination should be used on both ends
of the SCSI bus.
See the Comp.Periphs.Scsi FAQ (available on tsx-11 in
pub/linux/ALPHA/scsi) for more information about active
termination.
Section 1.2 : The kernel command line
Other parts of the documentation refer to a "kernel command line".
The kernel command line is a set of options you may specify
from either the LILO : prompt after an immage name, or in the
append field in your LILO configuration file (LILO .14
and newer use /etc/lilo.conf, older versions use /etc/lilo/config).
Boot your system with LILO, and hit one of the alt, control, or
shift keys when it first comes up to get a prompt. LILO
should respond with
:
At this prompt, you can select a kernel image to boot, or list
them with ?. Ie
:?
ramdisk floppy harddisk
To boot that kernel with the command line options you have
selected, simply enter the name followed by a white space delimited
list of options, terminating with a return.
Options take the form of
variable=valuelist
Where valuelist may be a single value or comma delimited list
of values with no whitespace. With the exception of root device,
individual values are numbers, and may be specified in either
decimal or hexadecimal.
Ie, to boot linux with an Adaptec 1520 clone not recognized
at bootup, you might type
:floppy aha152x=0x340,11,7,1
If you don't care to type all of this at boot time, it is also
possible to use the LILO configuration file "append" option
with LILO .13 and newer.
Ie,
append="aha152x=0x340,11,7,1"
Section 1.3 : A SCSI device shows up at all possible IDs
If this is the case, you have strapped the device at the same
address as the controller (typically 7, although some boards
use other addresses, with 6 being used by some Future Domain
boards).
Please change the jumper settings.
Section 1.4 : A SCSI device shows up at all possible LUNs
The device has buggy firmware.
As an interim sollution, you should try using the kernel
command line option
max_scsi_luns=1
If that works, there is a list of buggy devices
in the kernel sources in drivers/scsi/scsi.c in the variable
blacklist. Add your device to this list and mail the patch
to Linus Torvalds <Linus.Torvalds@cs.Helsinki.FI>.
Section 1.5 : You get sense errors when you know the devices are error free
Sometimes this is caused by bad cables or impropper termination.
See Section 1.1 : General Flakiness
Section 1.6 : A kernel configured with networking does not work.
The auto-probe routines for many of the network drivers
are not passive, and will interfere with operation with some
of the SCSI drivers.
Section 1.7 : Device detected, but unable to access.
A SCSI device is detected by the kernel, but you are unable to
access it - ie mkfs /dev/sdc, tar xvf /dev/rst2, etc fails.
You don't have a special file in /dev for the device.
Unix devices are identified as either block or character (block
devices go through the buffer cache, character devices do not) devices,
a major number (ie which driver is used - block major 8 corresponds
to SCSI disks) and a minor number (ie which unit is being accessed
through a given driver - ie character major 4, minor 0 is the first
virtual console, minor 1 the next, etc). However, accessing devices
through this separate namespace would break the unix/Linux metaphor of
"everything is a file," so character and block device special files
are created under /dev. This lets you access the raw third SCSI disk
device as /dev/sdc, the first serial port as /dev/ttyS0, etc.
The preferred method for creating a file is using the MAKEDEV script -
cd /dev
and run MAKEDEV (as root) for the devices you want to create - ie
./MAKEDEV sdc
wildcards "should" work - ie
./MAKEDEV sd\*
"should" create entries for all SCSI disk devices (doing this should
create /dev/sda through /dev/sdp, with fifteen partition entries for
each)
./MAKEDEV sdc\*
"should" create entries for /dev/sdc and all fifteen permissible
partitions on /dev/sdc, etc.
I say "should" because this is the standard unix behavior - the MAKEDEV
script in your installation may not conform to this behavior, or may
have restricted the number of devices it will create.
If MAKEDEV won't do the right magic for you, you'll have to create the
device entries by hand with the mknod command.
The block/character type, major, and minor numbers are specified for the
various SCSI devices in Subsection 4 : Device Files in the appropriate
section.
Take those numbers, and use (as root)
mknod /dev/device b|c major minor
ie -
mknod /dev/sdc b 8 32
mknod /dev/rst0 c 9 0
Section 1.8 : SCSI System Lockups
This could be one of a number of things. Also see the section for
your specific host adapter for possible further solutions.
There are cases where the lockups seem to occur when multiple devices
are in use at the same time. In this case, you can try contacting
the manufacturer of the devices and see if firmware upgrades are
available which would correct the problem. If possible, try a
different scsi cable, or try on another system. This can also
be caused by bad blocks on disks, or by bad handling of DMA by the
motherboard (for host adapters that do DMA). There are probably
many other possible conditions that could lead to this type of event.
Sometimes these problems occur when there are multiple devices in
use on the bus at the same time. In this case, if your host
adapter driver supports more than one outstanding command on the bus
at one time, try reducing this to 1 and see if this helps. If you
have tape drives or slow cdrom drives on the bus, this might not be
a practical solution.
Section 1.9 : Configuring and building the kernel
Unused SCSI drivers eat up valuable memory, aggravating
memory shortage problems on small systems because kernel
memory is unpagable.
So, you will want to build a kernel tuned for your
system, with only the drivers you need installed.
cd to /usr/src/linux
If you are using a root device other than the current
one, or something other than 80x25 VGA, and you are
writing a boot floppy, you should edit the makefile,
and make sure the
ROOT_DEV =
and
SVGA_MODE =
lines are the way you want them.
If you've installed any patches, you may wish to guarantee that all
files are rebuilt. If this is the case, you should type
make mrproper
Irregardless of weather you ran make mrproper, type
make config
and answer the configuration questions. Then run
make depend
and finally
make
Once the build completes, you may wish to update the
lilo configuration, or write a boot floppy. A boot floppy
may be made by running
make zdisk
Section 1.10 : LUNS other than 0 don't work
Many SCSI devices are horrendously broken, lock the SCSI
bus up solid, and do other bad things when you attempt to
talk to them at a logical unit someplace other than zero.
So, by default recent versions of the Linux kernel will not
probe luns other than 0. To work arround this, you need to
the max_scsi_luns command line option, or recompile the kernel
wiuth the CONFIG_SCSI_MULTI_LUN option.
Usually, you'll put
max_scsi_luns=8
on your LILO command line.
If your multi-LUN devices still aren't detected correctly after
trying one of these fixes (as the case will be with many old
SCSI->MFM, RLL, ESDI, SMD, and similar bridge boards), you'll
be thwarted by this piece of code
/* Some scsi-1 peripherals do not handle lun != 0.
I am assuming that scsi-2 peripherals do better */
if((scsi_result[2] & 0x07) == 1 &&
(scsi_result[3] & 0x0f) == 0) break;
in scan_scsis() in drivers/scsi/scsi.c. Delete this code,
and you should be fine.
Section 2 : Reporting Bugs
The Linux SCSI developers don't necessarily maintain old revisions
of the code due to space constraints. So, if you are not running the
latest publically released Linux kernel (note that many of the Linux
distributions, such as MCC, SLS, Yggdrasil, etc. often lag one or even
twenty patches behind this) chances are we will be unable to solve your
problem. So, before reporting a bug, please check to see if it exists
with the latest publically available kernel.
If after upgrading, and reading this document thoroughly, you still
believe that you have a bug, please mail a bug report to the SCSI channel
of the mailing list where it will be seen by many of the people who've
contributed to the Linux SCSI drivers.
In your bug report, please provide as much information as possible
regarding your hardware configuration, the exact text of
all of the messages that Linux prints when it boots, when the
error condition occurs, and where in the source code the error
is. Use the procedures outlined in Section 2.1 : Capturing
messages and Section 2.2 : Locating the source of a panic().
Failure to provide the maximum possible amount of information
may result in misdiagnosis of your problem, or developers
deciding that there are other more interesting problems to
fix.
The bottom line is that if we can't reproduce your bug, and you can't
point at us what's broken, it won't get fixed.
Section 2.1 : Capturing messages
If you are not running a kernel message logging system :
Insure that the /proc filesystem is mounted.
grep proc /etc/mtab
If the /proc filesystem is not mounted, mount it
mkdir /proc
chmod 755 /proc
mount -t proc /proc /proc
Copy the kernel revision and messages into a log file
cat /proc/version > /tmp/log
cat /proc/kmsg >> /tmp/log
Type CNTRL-C after a second or two.
If you are running some logger, you'll have to poke through the
appropriate log files (/etc/syslog.conf should be of some use
in locating them), or use dmesg.
If Linux is not yet bootstrapped, format a floppy diskette under DOS.
Note that if you have a distribution which mounts the root diskette off of
floppy rather than RAM drive, you'll have to format a diskette readable
in the drive not being used to mount root or use their ramdisk boot option.
Boot Linux off your distribution boot floppy, preferably in single user mode
using a RAM disk as root.
mkdir /tmp/dos
Insert the diskette in a drive not being used to mount root, and
mount it. Ie
mount -t msdos /dev/fd0 /tmp/dos
or
mount -t msdos /dev/fd1 /tmp/dos
Copy your log to it
cp /tmp/log /tmp/dos/log
Unmount the DOS floppy
umount /tmp/dos
And shutdown Linux
shutdown
Reboot into DOS, and using your favorite communications software include
the log file in your trouble mail.
Section 2.2 : Locating the source of a panic()
Like other unices, when a fatal error is encountered, Linux calls the
kernel panic() function. Unlike other unices, Linux doesn't dump
core to the swap or dump device and reboot automatically. Instead,
a useful summary of state information is printed for the user to
manually copy down. Ie :
Unable to handle kernel NULL pointer dereference at virtual address c0000004
current->tss,cr3 = 00101000, %cr3 = 00101000
*pde = 00102027
*pte = 00000027
Oops: 0000
EIP: 0010:0019c905
EFLAGS: 00010002
eax: 0000000a ebx: 001cd0e8 ecx: 00000006 edx: 000003d5
esi: 001cd0a8 edi: 00000000 ebp: 00000000 esp: 001a18c0
ds: 0018 es: 0018 fs: 002b gs: 002b ss: 0018
Process swapper (pid: 0, process nr: 0, stackpage=001a09c8)
Stack: 0019c5c6 00000000 0019c5b2 00000000 0019c5a5 001cd0a8 00000002 00000000
001cd0e8 001cd0a8 00000000 001cdb38 001cdb00 00000000 001ce284 0019d001
001cd004 0000e800 fbfff000 0019d051 001cd0a8 00000000 001a29f4 00800000
Call Trace: 0019c5c6 0019c5b2 0018c5a5 0019d001 0019d051 00111508 00111502
0011e800 0011154d 00110f63 0010e2b3 0010ef55 0010ddb7
Code: 8b 57 04 52 68 d2 c5 19 00 e8 cd a0 f7 ff 83 c4 20 8b 4f 04
Aiee, killing interrupt handler
kfree of non-kmalloced memory: 001a29c0, next= 00000000, order=0
task[0] (swapper) killed: unable to recover
Kernel panic: Trying to free up swapper memory space
In swapper task - not syncing
Take the hexidecimal number on the EIP: line, in this case 19c905, and search
through /usr/src/linux/zSystem.map for the highest number not larger than
that address. Ie,
0019a000 T _fix_pointers
0019c700 t _intr_scsi
0019d000 t _NCR53c7x0_intr
That tells you what function its in. Recompile the source file which
defines that function file with debugging enabled, or the whole kernel
if you prefer by editing /usr/src/linux/Makefile and adding a "-g"
to the CFLAGS definition.
#
# standard CFLAGS
#
Ie,
CFLAGS = -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer -pipe
becomes
CFLAGS = -g -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer -pipe
Rebuild the kernel, incrementally or by doing a
make clean
make
Make the kernel bootable by creating an entry in your /etc/lilo.conf
for it
image = /usr/src/linux/zImage
label = experimental
and re-running LILO as root, or by creating a boot floppy
make zImage
Reboot and record the new EIP for the error.
If you have script installed, you may want to start it, as
it will log your debugging session to the typescript file.
Now, run
gdb /usr/src/linux/tools/zSystem
and enter
info line *<your EIP>
Ie,
info line *0x19c905
To which GDB will respond something like
(gdb) info line *0x19c905
Line 2855 of "53c7,8xx.c" starts at address 0x19c905 <intr_scsi+641>
and ends at 0x19c913 <intr_scsi+655>.
Record this information. Then, enter
list <line number>
Ie,
(gdb) list 2855
2850 /* printk("scsi%d : target %d lun %d unexpected disconnect\n",
2851 host->host_no, cmd->cmd->target, cmd->cmd->lun); */
2852 printk("host : 0x%x\n", (unsigned) host);
2853 printk("host->host_no : %d\n", host->host_no);
2854 printk("cmd : 0x%x\n", (unsigned) cmd);
2855 printk("cmd->cmd : 0x%x\n", (unsigned) cmd->cmd);
2856 printk("cmd->cmd->target : %d\n", cmd->cmd->target);
2857 if (cmd) {
2858 abnormal_finished(cmd, DID_ERROR << 16);
2859 }
2860 hostdata->dsp = hostdata->script + hostdata->E_schedule /
2861 sizeof(long);
2862 hostdata->dsp_changed = 1;
2863 /* SCSI PARITY error */
2864 }
2865
2866 if (sstat0_sist0 & SSTAT0_PAR) {
2867 fatal = 1;
2868 if (cmd && cmd->cmd) {
2869 printk("scsi%d : target %d lun %d parity error.\n",
Obviously, quit will take you out of GDB.
Record this information too, as it will provide a context incase the
developers' kernels differ from yours.
Section 3 : Modules
This section gives specific details regarding the support for loadable
kernel modules and how it relates to SCSI.
Section 3.1 : General Information
Loadable modules are a means by which the user or system administrator
can load files into the kernel's memory in such a way that the kernel's
capabilities are expanded. The most common usages of modules are for
drivers to support hardware, or to load filessytems.
There are several advantages of modules for SCSI. One is that a
system administrator trying to maintain a large number of machines can
use a single kernel image for all of the machines, and then load
kernel modules to support hardware that is only present on some
machines.
It is also possible for someone trying to create a distribution to use
a script on the bootable floppy to query for which modules to be
loaded. This saves memory that would otherwise be wasted on unused
drivers, and it would also reduce the possibility that a probe for a
non-existant card would screw up some other card on the system.
Modules also work out nicely on laptops, which tend to have less
memory than desktop machines, and people tend to want to keep the
kernel image as small as possible and load modules as required. Also,
modules makes supporting PCMCIA SCSI cards on laptops somewhat easier,
since you can load and unload the driver as the card is
inserted/removed. [Note: currently the qlogic and 152x drivers support
PCMCIA].
Finally, there is the advantage that kernel developers can more easily
debug and test their drivers, since testing a new driver does not
require rebooting the machine (provided of course that the machine has
not completely crashed as a result of some bug in the driver).
Although modules are very nice, there is one limitation. If your root
disk partition is on a scsi device, you will not be able to use
modularized versions of scsi code required to access the disk. This
is because the system must be able to mount the root partition before
it can load any modules from disk. There are people thinking about
ways of fixing the loader and the kernel so that the kernel can
self-load modules prior to attempting to mount the root filesystem,
so at some point in the future this limitation may be lifted.
Section 3.2 : Module support in the 1.2.N kernel.
In the 1.2.N series of kernels, there is partial support for SCSI
kernel modules. While none of the high level drivers (such as disk,
tape, etc) can be used as modules, most of the low level drivers
(i.e. 1542, 1522) can be loaded and unloaded as required. Each time
you load a low-level driver, the driver first searches for cards that
can be driven. Next, the bus is scanned for each card that is found,
and then the internal data structures are set up so as to make it
possible to actually use the devices attached to the cards that the
driver is managing.
When you are through with a low-level driver, you can unload
it. You should keep in mind that usage counts are maintained based upon
mounted filesystems, open files, etc, so that if you are still using a
device that the driver is managing, the rmmod utillity will tell you that
the device is still busy and refuse to unload the driver. When the driver
is unloaded, all of the associated data structures are also freed so that
the system state should be back to where it was before the module was loaded.
This means that the driver could be reloaded at a later time if required.
Section 3.3 : Module support in the 1.3.N kernel.
In the 1.3 series of kernels, the scsi code is completely modularized.
This means that you can start with a kernel that has no scsi support
whatsoever, and start loading modules and you will eventually end up
with complete support.
If you wish, you can compile some parts of the SCSI code into the kernel
and then load other parts later - it is all up to you how much gets loaded
at runtime and how much is linked directly into the kernel.
If you are starting with a kernel that has no support whatsoever for
SCSI, then the first thing you will need to do is to load the scsi
core into the kernel - this is in a module called "scsi_mod". You
will not be able to load any other scsi modules until you have this
loaded into kernel memory. Since this does not contain any low-level
drivers, the act of loading this module will not scan any busses, nor
will it activate any drivers for scsi disks, tapes, etc. If you answered
'Y' to the CONFIG_SCSI question when you built your kernel, you will not
need to load this module.
At this point you can add modules in more or less any order to achieve
the desired functionality. Usage counts are interlocks are used to
prevent unloading of any component which might still be in use, and
you will get a message from rmmod if a module is still busy.
The high level drivers are in modules named "sd_mod", "sr_mod", "st",
and "sg", for disk, cdrom, tape, and scsi generics support
respectively. When you load a high level driver, the device list for
all attached hosts is examined for devices which the high level driver
can drive, and these are automatically activated.
The use of modules with low level drivers were described in the
Section 3.2. When a low-level driver is loaded, the bus is scanned,
and each device is examined by each of the high level drivers to see
if they recognize it as something that they can drive - anything
recognized is automatically attached and activated.
Section 4 : Hosts
This section gives specific information about the various host adapters that
are supported in some way or another under linux.
Section 4.1 : Supported and Unsupported Hardware
Drivers in the distribution kernel :
Adaptec 152x, Adaptec 154x (DTC 329x boards usually work, but are unsupported),
Adaptec 174x, Adaptec 274x/284x (294x support requires a newer version of the
driver), EATA-DMA protocol compilant boards (all DPT PMXXXXX/XX and
SKXXXXX/XX except the PM2001, some boards from NEC and ATT), Future Domain
850, 885, 950, and other boards in that series (but not the 840, 841, 880,
and 881 boards unless you make the appropriate patch), Future Domain 16x0 with
TMC-1800, TMC-18C30, or TMC-18C50 chips, NCR53c8xx,PAS16 SCSI ports, Seagate
ST0x, Trantor T128/T130/T228 boards, Ultrastor 14F, 24F, and 34F, and Western
Digital 7000.
MCA :
MCA boards which are compatable with a supported board (ie,
Adaptec 1640 and Buslogic 640) will work.
Alpha drivers :
Many ALPHA drivers are available at
ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi
Drivers which will work with modifications
eata_dma:
DPT PM2001
NCR53c8x0/7x0:
A NCR53c8xx driver has been developed, but currently will not work
with NCR53c700, NCR53c700-66, NCR53c710, and NCR53c720 chips. A list
of changes needed to make each of these chips work follows, as well
as a summary of the complexity.
NCR53c720 (trivial) - detection changes, initializaion changes, change
fixup code to translate '810 register addresses to
'7xx mapping.
NCR53c710 (trivial) - detection changes, initialization changes,
of assembler, change fixup code to translate '810 register
addresses to '7xx mapping, change interrupt handlers to treat
IID interrupt from INTFLY instruction to emulate it.
NCR53c700, NCR53c700-66 (very messy) - detection changes,
initialization changes, modification of NCR code to not use DSA,
modification of Linux code to handle context switches.
SCSI hosts that will not work :
All parallel->SCSI adapters, Rancho SCSI boards, and Grass Roots SCSI
boards.
SCSI hosts that will NEVER work :
Non Adaptec compatable DTC boards (including the 3270 and 3280).
CMD SCSI boards.
Aquiring programming information requires a non-disclosure agreement
with DTC/CMD. This means that it would be impossible to distribute a
Linux driver if one were written, since complying with the NDA would
mean distributing no source, in violation of the GPL, and complying
with the GPL would mean distributing source, in violation of the NDA.
If you want to run Linux on some other unsupported piece of hardware, your
options are to either write a driver yourself (Eric Youngdale and I are
usually willing to answer technical questions concerning the Linux
SCSI drivers) or to commision a driver (Normal consulting rates
mean that this will not be a viable option for personal use).
Section 4.1.1 : Multiple host adapters
With some host adapters (see Section 9.7 : Buyers' Guide :
Feature Comparison), you can use multiple host adapters of the
same type in the same system. With multiple adapters of the
same type in the same system, generally the one at the lowest
address will be scsi0, the one at the next address scsi1, etc.
In all cases, it is possible to use multiple host adapters of
different types, provided that none of their addresses conflict.
SCSI controllers are scanned in the order specified in the
builtin_scsi_hosts[] array in drivers/scsi/hosts.c, with
the order currently being
Ultrastor 14/34F, Ultrastor 14F,, Adaptec 151x/152x, Buslogic,
Adaptec 154x, Adaptec 174x, AIC7XXX, AM53C974, Future Domain 16x0,
Allways IN2000, Generic NCR5380, QLOGIC, PAS16, Seagate,
Trantor T128/T130, NCR53c8xx, EATA-DMA, WD7000, debugging driver.
In most cases (ie, you aren't trying to use both
Buslogic and Adaptec drivers), this can be changed to suit your
needs (ie, keeping the same devices when new SCSI devices
are added to the system on a new controller) by moving the individual
entries.
Section 4.2 : Common Problems
Section 4.2.1 : SCSI timeouts
Make sure interrupts are enabled correctly, and there are no
IRQ, DMA, or address conflicts with other boards.
Section 4.2.2 : Failure of autoprobe routines on boards that rely on
BIOS for autoprobe.
If your SCSI adapter is one of the following :
Adaptec 152x, Adaptec 151x, Adaptec AIC-6260,
Adaptec AIC-6360, Future Domain 1680, Future Domain TMC-950,
Future Domain TMC-8xx, Trantor T128, Trantor T128F,
Trantor T228F, Seagate ST01, Seagate ST02, or a
Western Digital 7000
and it is not detected on bootup, ie you get a
scsi : 0 hosts
message or a
scsi%d : type
message is not printed for each supported SCSI adapter installed
in the system, you may have a problem with the autoprobe routine
not knowing about your board.
Autodetection will fail for drivers using the BIOS for autodetection
if the BIOS is disabled. Double check that your BIOS is enabled,
and not conflicting with any other peripherial BIOSes.
Autodetection will also fail if the board's "signature" and/or
BIOS address don't match known ones.
If the BIOS is installed, please use DOS and DEBUG to
find a signature that will detect your board -
Ie, if your board lives at 0xc8000, under DOS do
debug
d c800:0
q
and send a message to the SCSI channel of the mailing list with
the ASCII message, with the length and offset from the base
address (ie, 0xc8000). Note that the EXACT text is required,
and you should provide both the hex and ASCII portions of
the text.
If no BIOS is installed, and you are using an Adaptec 152x,
Trantor T128, or Seagate driver, you can use command line
or compile time overrides to force detection.
Please consult the appropriate subsection for your SCSI board
as well as Section 1.1 :
Section 4.2.3 : Failure of boards using memory mapped I/O
(This include the Trantor T128 and Seagate boards, but not the
Adaptec, Generic NCR5380, PAS16, and Ultrastor drivers)
This is often caused when the memory mapped I/O ports
are incorrectly cached. You should have the board's
address space marked as uncachable in the XCMOS settings.
If this is not possible, you will have to disable cache
entirely.
If you have manually specified the address of the board,
remember that Linux needs the actual address of the board,
and not the 16 byte segment the documentation may refer to.
Ie, 0xc8000 would be correct, 0xc800 would not work
and could cause memory corruption.
Section 4.2.4 : "kernel panic : cannot mount root device" when booting
an ALPHA driver boot floppy
You'll need to edit the binary image of the kernel (before
or after writing it out to disk), and modify a few two byte
fields (little endian) to gurantee that it will work on your
system.
1. default swap device at offset 502, this should be set to 0x00 0x00
2. ram disk size at offset 504, this should be set to the size
of the boot floppy in K - ie, 5.25" = 1200, 3.5" = 1440.
This means the bytes are
3.5" : 0xA0 0x05
5.25" : 0xB0 0x04
3. root device offset at 508, this should be 0x00 0x00, ie the boot
device.
dd or rawrite the file to a disk. Insert the disk in the
first floppy drive, wait until it prompts you to insert
the root disk, and insert the root floppy from your
distribution.
Section 4.2.5 : Installing a device driver not included with the distribution
kernel
You need to start with the version of the kernel used by the
driver author. This revision may be alluded to in the documentation
included with the driver.
Various recent kernel revisions can be found at
nic.funet.fi:/pub/OS/Linux/PEOPLE/Linus
as linux-version.tar.gz
They are also mirrored at tsx-11.mit.edu and various other sites.
cd to /usr/src.
Remove your old Linux sources, if you want to keep a backup copy
of them
mv linux linux-old
Untar the archive
gunzip < linux-0.99.12.tar.gz | tar xvfp -
Apply the patches. The patches will be relative to some directory
in the filesystem. By examining the output file lines in the patch
file (grep for ^---), you can tell where this is - ie patches with
these lines
--- ./kernel/blk_drv/scsi/Makefile
--- ./config.in Wed Sep 1 16:19:33 1993
would have the files relative to /usr/src/linux.
Untar the driver sources at an appropriate place - you
can type
tar tfv patches.tar
to get a listing, and move files as necessary (The SCSI driver files
should live in /usr/src/linux/kernel/drivers/scsi)
Either cd to the directory they are relative to and type
patch -p0 < patch_file
or tell patch to strip off leading path components. Ie,
if the files started with
--- linux-new/kernel/blk_drv/scsi/Makefile
and you wanted to apply them while in /usr/src/linux, you
could cd to /usr/src/linux and type
patch -p1 < patches
to strip off the "linux-new" component.
After you have applied the patches, look for any patch rejects,
which will be the name of the rejected file with a # suffix appended.
find /usr/src/linux/ -name "*#" -print
If any of these exist, look at them. In some cases, the
differences will be in RCS identifiers and will be harmless,
in other cases, you'll have to manually apply important
parts. Documentation on diff files and patch is beyond the
scope of this document.
See also Section 1.8 : Configuring and building the kernel
Section 4.2.6 : Installing a driver that has no patches
In some cases, a driver author may not offer patches with
the .c and .h files which comprise his driver, or the patches
may be against an older revision of the kernel and not go
in cleanly.
1. Copy the .c and .h files into /usr/src/linux/drivers/scsi
2. Add the configuration option
Edit /usr/src/linux/config.in, and add a line in the
*
* SCSI low-level drivers
*
section, add a boolean configuration variable for your
driver. Ie,
bool 'Allways IN2000 SCSI support' CONFIG_SCSI_IN2000 y
3. Add the makefile entries
Edit /usr/src/linux/drivers/scsi/Makefile, and add
an entry like
ifdef CONFIG_SCSI_IN2000
SCSI_OBS := $(SCSI_OBJS) in2000.o
SCSI_SRCS := $(SCSI_SRCS) in2000.c
endif
before the
scsi.a: $(SCSI_OBJS)
line in the makefile, where the .c file is the .c
file you copied in, and the .o file is the basename
of the .c file with a .o suffixed.
4. Add the entry points
Edit /usr/src/linux/drivers/scsi/hosts.c, and
add a #inlclude for the header file, conditional
on the CONFIG_SCSI preprocessor define you
added to the configuration file. Ie, after
#ifdef CONFIG_SCSI_GENERIC_NCR5380
#include "g_NCR5380.h"
#endif
you might add
#ifdef CONFIG_SCSI_IN2000
#include "in2000.h"
#endif
You will also need to add the Scsi_Host_Template
entry into the scsi_hosts[] array. Take a look
into the .h file, and you should find a #define that
looks something like this :
#define IN2000 {"Always IN2000", in2000_detect, \
in2000_info, in2000_command, \
in2000_queuecommand, \
in2000_abort, \
in2000_reset, \
NULL, \
in2000_biosparam, \
1, 7, IN2000_SG, 1, 0, 0}
the name of the preprocessor define, and add
it into the scsi_hosts[] array, conditional on
definition of the preprocessor symbol you used
in the configuration file.
Ie, after
#ifdef CONFIG_SCSI_GENERIC_NCR5380
GENERIC_NCR5380,
#endif
you might add
#ifdef CONFIG_SCSI_IN2000
IN2000,
#endif
See also Section 1.8 : Configuring and building the kernel
Section 4.2.7 : Failure of a PCI board in a Compaq System
A number of Compaq systems map the 32-bit BIOS extensions used
to probe for PCI devices into memory which is inaccessable to
the Linux kernel due to the memory layout. If Linux is
unable to detect a supported PCI SCSI board, and the
kernel tells you something like
pcibios_init: entry in high memory, unable to access
Grab
ftp:/pub/softpaq/Software-Solutions/SP0921.EXE
which is a self-extracting archive of a program which will
relocate the BIOS32 code.
Section 4.3 : Adaptec 152x, 151x, Sound Blaster 16 SCSI, SCSI Pro,
Gigabyte, and other AIC 6260/6360 based products (Standard)
Supported Configurations :
BIOS addresses : 0xd8000, 0xdc000, 0xd0000, 0xd4000, 0xc8000, 0xcc000, 0xe0000,
0xe4000.
Ports : 0x140, 0x340
IRQs : 9, 10, 11, 12
DMA is not used
IO : port mapped
Autoprobe :
Works with many boards with an installed BIOS. All
other boards, including the Adaptec 1510, and Sound Blaster16 SCSI
must use a kernel command line or compile time override.
Autoprobe Override :
Compile time :
Define PORTBASE, IRQ, SCSI_ID, RECONNECT, PARITY as appropriate, see Defines
kernel command line : aha152x=<PORTBASE>[,<IRQ>[,<SCSI-ID>[,<RECONNECT>[,<PARITY>]]]]
SCSI-ID is the SCSI ID of the HOST adapter, not of any devices you have installed
on it. Usually, this should be 7.
To force detection at 0x340, IRQ 11, at SCSI-ID 7, allowing
disconnect/reconnect, you would use the following command line
option :
aha152x=0x340,11,7,1
Antiquity Problems, fix by upgrading :
1. The driver fails with VLB boards. There was a timing problem
in kernels older than revision 1.0.5.
Defines :
AUTOCONF : use configuration the controller reports (only 152x)
IRQ : override interrupt channel (9,10,11 or 12) (default 11)
SCSI_ID : override SCSI ID of AIC-6260 (0-7) (default 7)
RECONNECT : override target disconnect/reselect (set to non-zero to
allow, zero to disable)
DONT_SNARF : Don't register ports (pl12 and below)
SKIP_BIOSTEST : Don't test for BIOS signature (AHA-1510 or disabled BIOS)
PORTBASE : Force port base. Don't try to probe
Section 4.4 : Adaptec 154x, AMI FastDisk VLB, Buslogic, DTC 329x (Standard)
Supported Configurations :
Ports : 0x330 and 0x334
IRQs : 9, 10, 11, 12, 14, 15
DMA channels : 5, 6, 7
IO : port mapped, bus master
Autoprobe : will detect boards at 0x330 and 0x334 only.
Autoprobe override :
aha1542=<PORTBASE>[,<BUSON>,<BUSOFF>[,<DMASPEED>]]
Note: No-suffix boards, and early 'A' suffix boards do not support
scatter/gather, and thus don't work. However, they can be made to
work for some definition of the word works if AHA1542_SCATTER is
changed to 0 in drivers/scsi/aha1542.h.
Note: Buslogic makes a series of boards that are software compatible with
the Adaptec 1542, and these come in ISA, VLB and EISA flavors.
Antiquity Problems, fix by upgrading :
1. Linux kernel revisions prior to .99.10 don't support the 'C'
revision.
2. Linux kernel revisions prior to .99.14k don't support the 'C'
revision options for
- BIOS support for the extended mapping for disks > 1G
- BIOS support for > 2 drives
- BIOS support for autoscanning the SCSI bus
3. Linux kernel revisions prior to .99.15e don't support the 'C'
with the BIOS support for > 2 drives turned on and the
BIOS support for the extended mapping for disks > 1G turned off.
4. Linux kernel revisions prior to .99.14u don't support the 'CF'
revisions of the board.
5. Linux kernel revisions prior to 1.0.5 have a race condition
when multiple devices are accessed at the same time.
Common problems :
1. There are unexpected errors with a 154xC or 154xCF board,
Early examples of the 154xC boards have a high slew rate on
one of the SCSI signals, which results in signal reflections
when cables with the wrong impedance are used.
Newer boards aren't much better, and also suffer from extreme
cabling and termination sensitivity.
See also Common Problems #2 and #3 and Section 1 : Common Problems,
Subsection 1.1 : General Flakiness
2. There are unexpected errors with a 154xC or 154x with
both internal and external devices connected.
This is probably a termination problem. In order to
use the software option to disable host adapter termination,
you must turn switch 1 off.
See also Common Problems #1 and #3 and Section 1 : Common Problems,
Subsection 1.1 : General Flakiness
3. The SCSI subsystem locks up completely.
There are cases where the lockups seem to occur when multiple devices
are in use at the same time. In this case, you can try contacting
the manufacturer of the devices and see if firmware upgrades are
available which would correct the problem. As a last resort, you
can go into aha1542.h and change AHA1542_MAILBOX to 1. This will
effectively limit you to one outstanding command on the scsi bus at
one time, and may help the situation. If you have tape drives or
slow cdrom drives on the bus, this might not be a practical solution.
See also Common Problems #1 and #2 and
Section 1.1 : Common Problems : General Flakiness
Section 1.8 : Common Problems : SCSI Lockups
4. An "Interrupt received, but no mail" message is printed on bootup
and your SCSI devices are not detected.
Disable the BIOS options to support the extended mapping for
disks > 1G, support for > 2 drives, and for autoscanning the
bus. Or, upgrade to Linux .99.14k or newer.
5. If infinite timeout errors occur on 'C' revision boards, you may need
to go into the Adaptec setup program and enable synchronous
negotiation.
Section 4.5 : Adaptec 174x
Supported Configurations :
Slots : 1-8
Ports : EISA board, not applicable
IRQs : 9, 10, 11, 12, 14, 15
DMA Channels : EISA board, not applicable
IO : port mapped, bus master
Autoprobe : works with all supported configurations
Autoprobe override : none
Note: This board has been discontinued by Adaptec.
Common Problems :
1. If the Adaptec 1740 driver prints the message
"aha1740: Board detected, but EBCNTRL = %x, so disabled it."
your board was disabled because it was not running in enhanced
mode. Boards running in standard 1542 mode are not supported.
Section 4.6 : Adaptec 274x, 284x (Standard) 294x (ALPHA)
A newer version which also supports the Adaptec 294x boards
is available at
ftp://ftp.ims.com/pub/Linux/aic7xxx
Supported Configurations
274x 284x 294x
EISA Slots : 1-12 N/A N/A
Ports : N/A ALL ALL
IRQs : ALL ALL ALL
DMA Channels : N/A ALL N/A
IO : port mapped, bus master
Autoprobe Override :
kernel command line : aha274x=extended
(to force extended mapping)
Notes:
1. BIOS MUST be enabled
2. The B channel on 2742AT boards is ignored.
3. CONFIG_PCI must be set if you are using a PCI board.
Section 4.7 : Allways IN2000 (STANDARD)
Ports : 0x100, 0x110, 0x200, 0x220
IRQs : 10, 11, 14, 15
DMA is not used
IO : port mapped
Autoprobe : BIOS not required
Autoprobe override : none
Common Problems :
1. There are known problems in systems with IDE drives and with
swapping.
Section 4.8 : EATA: DPT Smartcache, Smartcache Plus, Smartcache III (Standard)
Supported boards: all, that support the EATA-DMA protocol (no PM2001).
DPT Smartcache: PM2011 PM2012A
PM2012B
Smartcache III: PM2021 PM2022 PM2024
PM2122 PM2124
PM2322
SmartRAID : PM3021 PM3222 PM3224
many of those boards are also available as SKXXXX versions,
which are supported as well.
Supported Configurations :
Slots : ALL
Ports : ALL
IRQs : ALL level & edge triggered
DMA Channels : ISA ALL, EISA/PCI not applicable
IO : port mapped, bus master
SCSI Channels: ALL
Autoprobe : works with all supported configurations
Autoprobe Override :
Compile time : diskgeometry in eata_dma.h for unusual disk geometries
which came from the usage of the old DPTFMT utility.
The latest version of the EATA-DMA driver and a Slackware bootdisk should
be available on:
ftp.uni-mainz.de:/pub/Linux/arch/i386/system/EATA/
Common Problems :
1. The IDE driver detects the ST-506 interface of the EATA board.
1.1 This will look like similar to one of the following 2 examples:
hd.c: ST-506 interface disk with more than 16 heads detected,
probably due to non-standard sector translation. Giving up.
(disk %d: cyl=%d, sect=63, head=64)
hdc: probing with STATUS instead of ALTSTATUS
hdc: MP0242 A, 0MB w/128KB Cache, CHS=0/0/0
hdc: cannot handle disk with 0 physical heads
hdd: probing with STATUS instead of ALTSTATUS
hdd: MP0242 A, 0MB w/128KB Cache, CHS=0/0/0
hdd: cannot handle disk with 0 physical heads
If the IDE driver gets into trouble because of this, ie. you can't
access your (real) IDE hardware, change the IO Port and/or the IRQ of
the EATA board.
1.2 If the IDE driver finds hardware it can handle ie. harddisks with
a capacity <=504MB, it will allocate the IO Port and IRQ, so that
the eata driver can't utilize them. In this case also change IO Port
and IRQ (!= 14,15).
2. Some old SK2011 boards have a broken firmware. Please contact DPT's
customer support for an update.
Notes:
1. CONFIG_PCI must be set if you are using a PCI board.
Section 4.9 : Future Domain 16x0 with TMC-1800, TMC-18C30, TMC-18C50,
or TMC-36C70 chip
Supported Configurations :
BIOSs : 2.0, 3.0, 3.2, 3.4, 3.5
BIOS Addresses : 0xc8000, 0xca000, 0xce000, 0xde000
Ports : 0x140, 0x150, 0x160, 0x170
IRQs : 3, 5, 10, 11, 12, 14, 15
DMA is not used
IO : port mapped
Autoprobe : works with all supported configurations, requires
installed BIOS
Autoprobe Override : none
Antiquity Problems, fix by upgrading :
1. Old versions do not support the TMC-18C50 chip, and will fail with
newer boards.
2. Old versions will not have the most current BIOS signatures for
autodetection.
3. Versions prior to the one included in Linux 1.0.9 and 1.1.6
don't support the new SCSI chip or 3.4 BIOS.
Notes :
The Future Domain BIOS often scans for SCSI-devices from highest
ID to 0, in reverse order of other SCSI BIOSes. sda will be the last
"drive letter" (ie, D: rather than C:). You may also need to use a
a disktab override for LILO.
Section 4.10 : Generic NCR5380 / T130B
Supported and Unsupported Configurations :
Ports : all
IRQs : all
DMA channels - DMA is not used
IO : port mapped
Autoprobe : none
Autoprobe Override :
Compile time : Define GENERIC_NCR5380_OVERRIDE to be an array of tupples
with port, irq, dma, board type - ie
#define GENERIC_NCR5380_OVERRIDE {{0x330, 5, DMA_NONE, BOARD_NCR5380}}
for a NCR5380 board at port 330, IRQ 5.
#define GENERIC_NCR5380_OVERRIDE {{0x350, 5, DMA_NONE, BOARD_NCR53C400}}
for a T130B at port 0x350.
Older versions of the code eliminate the BOARD_* entry.
The symbolic IRQs IRQ_NONE and IRQ_AUTO may be used.
kernel command line : ncr5380=port,irq
ncr5380=port,irq,dma
ncr53c400=port,irq
255 may be used for no irq, 254 for irq autoprobe.
Common Problems :
1. Using the T130B board with the old (pre public release 6) generic
NCR5380 driver which doesn't support the ncr53c400 command
line option.
The NCR5380 compatable registers are offset eight from
the base address. So, if your address is 0x350, use
ncr5380=0x358,254
on the kernel command line.
Antiquity problems, fix by upgrading :
1. The kernel locks up during disk access with T130B or other
NCR53c400 boards
Pre-public release 6 versions of the Generic NCR5380
driver didn't support interrupts on these boards.
Upgrade.
Notes : the generic driver doesn't support DMA yet, and pseudo-DMA
isn't supported in the generic driver.
Section 4.11 : NCR53c8xx (Standard)
Supported and Unsupported Configurations :
Base addresses : ALL
IRQs : ALL
DMA channels : PCI, not applicable
IO : port mapped, busmastering
Autoprobe : requires PCI BIOS, uses PCI BIOS routines to
search for devices and read configuration space
The driver uses the pre-programmed values in some registers for
initialization, so a BIOS must be installed.
Antiquity Problems, fix by upgrading :
1. Older versions of Linux had a problem with swapping
See Section 5.2.7 : Disks : System Hangs When Swapping
2. Older versions of Linux didn't recognize '815 and '825
boards.
3. Distribution kernels include release 4 or 5 of the driver, which does
not support useful things like disconnect/reconnect (the most noticeable
effect of this being attempts to retension/rewind/file space a tape
lock you out of all SCSI devices), multiple host adapters, and
BIOSless operation.
The latest release of the driver is available at
ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/ncr53c810
Currently, this is a 1.2.10 and newer patch, although the next
release will be 1.3.x exclusively. These patches are NOT
entirely clean due to some ELF and other patches which were
in the baseline revision of my source tree, and if you
can't manually correct the (four) problems you should get,
you shouldn't use them. Note that only the newest patch is
needed; these are not incremental.
If you wish to run the newer NCR driver with a 1.3.x kernel
before then, Harald Evensen <Harald.Evensen@pvv.unit.no> has
adapted the patches for 1.3.x
ftp://ftp.pvv.unit.no/pub/Linux/ALPHA/ncr
These patches should be clean.
Please see all of the READMEs in these directories. You should
also join the NCR mailing list if you are interested in running
the ALPHA code, since interim bug fixes and announcements of the
next release are posted to this list.
To subscribe, send mail to majordomo@colorado.edu with
subscribe ncr53c810
in the text. You can unsubscribe by sending mail to the same address
and including
unsubscribe ncr53c810
in the text.
Common Problems :
1. Many people have encountered problems where the chip worked
fine under DOS, but failed under Linux with a timeout on
test 1 due to a lost interrupt.
This is often due to a mismatch between the IRQ hardware
jumper for a slot or mainboard device and the value set
in the CMOS setup. DOUBLE CHECK
- The IRQ you are using is used only by your onboard NCR chip,
or the slot an NCR board is installed in
- Any main board jumpers selecting the IRQ for the onboard
chip or slot match your CMOS setup.
It may also be due to PCI INTB, INTC, or INTD being selected
on a PCI board in a system which only supports PCI INTA. If you
are using an NCR board which has jumpers to select between PCI
interrupt lines, make sure you are using INTA.
Finally, PCI should be using level-sensitive rather
than edge triggered interrupts. Check that your board
is jumpered for level-sensitive, and if that fails
try edge-triggered because your system may be
broken.
This problem is especially common with Viglen some Viglen
motherboards, where the mainboard IRQ jumper settings are
NOT as documented in the manual. I've been told that what
claims to be IRQ5 is really IRQ9, your mileage will vary.
2. Lockups / other problems occur when using an S3 928, or Tseng
ET4000W32 PCI video board.
There are hardware bugs in at least some revisions of these
chips. Don't use them.
3. You get a message on boot up indicating that the I/O mapping
was disabled because base address 0 bits 0..1 indicated a
non I/O mapping
This is due to a BIOS bug in some machines which results in
dword reads of configuration regsisters returning the
high and low 16 bit words swapped.
4. Some systems have problems if PCI write posting, or CPU->
PCI buffering are enabled. If you have problems,
disable these options.
5. Some systems with the NCR SDMS software in an onboard BIOS
ROM and in the system BIOS are unable to boot DOS.
Disabling the image in one place should rectify this
problem.
6. If you encounter the message
"scsi%d: IRQ0 not free, detaching"
The NCR chip had a 0 stored in the PCI configuration register.
Either you have configuration problems (see Common Problem 1), or
you have a defective mainboard BIOS.
As a work arround, you could edit drivers/scsi/ncr53c7,8xx.c,
and change pci_init() so that you have
irq = my_irq;
before
return normal_init (tpnt, board, chip, (int) base,
(int) io_port, (int) irq, DMA_NONE, 1, bus, device_fn,
options);
7. Some systems have hideous, broken, BIOS chips. Don't
make any bug reports until you've made sure you have
the newest ROM from your vendor.
8. The command line overrides ncr53c810=xxx, etc. don't work.
In stock kernels, this is because their entry points are not included
in init/main.c, which is quite intentional :
The driver makes no attempt to avoid autoprobing for a board
where a command line override was used, so if an override
is used where the board actually showed up to the PCI
configuration routines, you'll have big problems.
The only reason you would need an override would be if the
PCI hardware + BIOS were broken, in which case certain error
recovery routines wouldn't work, rendering the override
less than useful.
Finally, nearly all of people who _think_ they need a command line
override do because they get configuration or other error messages
from the driver. If the driver says you have a configuration
problem, you have a broken system or a configuration problem
and no override is going to fix this.
If some one has gone and added the appropriate entry points to
init/main.c for command line overrides, they are totally unsupported
and may not work.
9. Certain NCR boards (most notably Nexstor) which don't use an
NCR BIOS get timeouts. Some of these ROMs handle synchronous
and transfers, negotiate for sync. transfers on power up,
and leave the drives in an unknown state. When the distribution
Linux NCR driver attempts to talk with them, it gets timeouts
and cannot recover because it won't do a bus reset or renegotiate.
If you run into this problem, you can either disable
synchronous transfers in the board's setup program, or
upgrade to a newer ALPHA release of the NCR driver which
will do synchronous negotiation.
Notes:
1. CONFIG_PCI must be set
Section 4.12 : Seagate ST0x/Future Domain TMC-8xx/TMC-9xx
Supported and Unsupported Configurations :
Base addresses : 0xc8000, 0xca000, 0xcc000, 0xce000, 0xdc000, 0xde000
IRQs : 3, 5
DMA channels : DMA is not used
IO : memory mapped
Autoprobe : probes for address only, IRQ is assumed to be 5,
requires installed BIOS.
Autoprobe Override :
Compile time : Define OVERRIDE to be the base address, CONTROLLER to
FD or SEAGATE as appropriate, and IRQ to the IRQ.
kernel command line : st0x=address,irq or tmc8xx=address,irq (only works
for .99.13b and newer)
Antiquity Problems, fix by upgrading :
1. Versions prior to the one in the Linux .99.12 kernel had a problem
handshaking with some slow devices, where
This is what happens when you write data out to the bus
1. Write byte to data register, data register is asserted to bus
2. time_remaining = 12us
3. wait while time_remaining > 0 and REQ is not asserted
4. if time_remaining > 0, assert ACK
5. wait while time remaining > 0 and REQ is asserted
6. deassert ACK
The problem was encountered in slow devices that do the command
processing as they read the command, where the REQ/ACK handshake
takes over 12us - REQ didn't go false when the driver expected it
to, so the driver ended up sending multiple bytes of data for
each REQ pulse.
2. With Linux .99.12, a bug was introduced when I fixed the arbitration
code, resulting in failed selections on some systems. This was
fixed in .99.13.
Common Problems :
1. There are command timeouts when Linux attempts to read the partition
table or do other disk access.
The board ships with the defaults set up for MSDOS, ie interrupts
are disabled. To jumper the board for interrupts, on the Seagate
use jumper W3 (ST01) or JP3 (ST02) and short pins F-G to select
IRQ 5.
2. The driver can't handle some devices, particularly cheap SCSI
tapes and CDROMs.
The Seagate ties the SCSI bus REQ/ACK handshaking into the PC bus
IO CHANNEL READY and (optionally) 0WS signals. Unfortunately, it
doesn't tell you when the watchdog timer runs out, and you have
no way of knowing for certain that REQ went low, and may end up
seeing one REQ pulse as multiple REQ pulses.
Dealing with this means using a tight loop to look for REQ to
go low, with a timeout incase you don't catch the transition due
to an interrupt, etc. This results in a performance decrease, so it
would be undesireable to apply this to all SCSI devices. Instead,
it is selected on a per-device basis with the "borken" field for
the given SCSI device in the scsi_devices array. If you run into
problems, you should try adding your device to the list of
devices for which borken is not reset to zero (currently,
only the TENEX CDROM drives).
3. A future domain board (specific examples include the 840,841,
880, and 881) doesn't work.
A few of the Future domain boards use the Seagate
register mapping, and have the MSG and CD bits of the
status register flipped.
You should edit seagate.h, swapping the definitions for
STAT_MSG and STAT_CD, and recompile the kernel with
CONTROLLER defined to SEAGATE and an appropriate
IRQ and OVERRIDE specified.
4. When attempting to fdisk your drive, you get error messages
indicating that the HDIO_REQ or HDIO_GETGEO ioctl failed,
or
You must set heads sectors and cylinders.
You can do this from the extra functions menu.
See Section 5.4 : Disks : Partitioning
5. After manually specifying the drive geometry, subsequent
attempts to read the partition table result in partition
boundary not on a cylinder boundary, physical and logical
boundaries don't match, etc. error messages.
See Section 5.4 : Disks : Partitioning
6. Some systems which worked prior to .99.13 fail with newer
versions of Linux. Older versions of Linux assigned the
CONTROL and DATA registers in an order different than that
outlined in the Seagate documentation, which broke on some
systems. Newer versions make the assignment in the correct
way, but this breaks other systems.
The code in seagate.c looks like this now :
cli();
DATA = (unsigned char) ((1 << target) | (controller_type == SEAGATE ? 0x80 : 0x40));
CONTROL = BASE_CMD | CMD_DRVR_ENABLE | CMD_SEL |
(reselect ? CMD_ATTN : 0);
sti();
Changing this to
cli();
CONTROL = BASE_CMD | CMD_DRVR_ENABLE | CMD_SEL |
(reselect ? CMD_ATTN : 0);
DATA = (unsigned char) ((1 << target) | (controller_type == SEAGATE ? 0x80 : 0x40));
sti()
may fix your problem.
Defines :
FAST or FAST32 will use blind transfers where possible
ARBITRATE will cause the host adapter to arbitrate for the
bus for better SCSI-II compatability, rather than just
waiting for BUS FREE and then doing its thing. Should
let us do one command per Lun when I integrate my
reorganization changes into the distribution sources.
SLOW_HANDSHAKE will allow compatability with broken devices that don't
handshake fast enough (ie, some CD ROM's) for the Seagate
code.
SLOW_RATE=x, x some number will let you specify a default
transfer rate if handshaking isn't working correctly.
Section 4.13 : PAS16 SCSI
Supported and Unsupported Configurations :
Ports : 0x388, 0x384, 0x38x, 0x288
IRQs : 10, 12, 14, 15
IMPORTANT : IRQ MUST be different from the IRQ used for the sound
portion of the board.
DMA is not used for the SCSI portion of the board
IO : port mapped
Autoprobe : does not require BIOS
Autoprobe Override :
Compile time : Define PAS16_OVERRIDE to be an array of port, irq
tupples. Ie
#define PAS16_OVERRIDE {{0x388, 10}}
for a board at port 0x388, IRQ 10.
kernel command line :
pas16=port,irq
Defines :
AUTOSENSE - if defined, REQUEST SENSE will be performed automatically
for commands that return with a CHECK CONDITION status.
PSEUDO_DMA - enables PSEUDO-DMA hardware, should give a 3-4X performance
increase compared to polled I/O.
PARITY - enable parity checking. Not supported
SCSI2 - enable support for SCSI-II tagged queueing. Untested
UNSAFE - leave interrupts enabled during pseudo-DMA transfers. You
only really want to use this if you're having a problem with
dropped characters during high speed communications, and even
then, you're going to be better off twiddling with transfersize.
USLEEP - enable support for devices that don't disconnect. Untested.
Common problems :
1. Command timeouts, aborts, etc.
You should install the NCR5380 patches that I posted to the net
some time ago, which should be integrated into some future alpha
release. These patches fix a race condition in earlier NCR5380
driver cores, as well as fixing support for multiple devices on
NCR5380 based boards.
If that fails, you should disable the PSEUDO_DMA option by
changing the #define PSEUDO_DMA line in drivers/scsi/pas16.c to #undef
PSEUDO_DMA.
Note that the later should be considered a last resort, because
there will be a severe performance degradation.
Section 4.14 : Trantor T128/T128F/T228
Supported and Unsupported Configurations :
Base addresses : 0xcc000, 00xc8000, 0xdc000, 0xd8000
IRQs : none, 3, 5, 7 (all boards)
10, 12, 14, 15 (T128F only)
DMA is not used.
IO : memory mapped
Autoprobe : works for all supported configurations, requires
installed BIOS.
Autoprobe Override :
Compile time : Define T128_OVERRIDE to be an array of address, irq
tupples. Ie
#define T128_OVERRIDE {{0xcc000, 5}}
for a board at address 0xcc000, IRQ 5.
The symbolic IRQs IRQ_NONE and IRQ_AUTO may be used.
kernel command line : t128=address,irq
-1 may be used for no irq, -2 for irq autoprobe.
Defines :
AUTOSENSE - if defined, REQUEST SENSE will be performed automatically
for commands that return with a CHECK CONDITION status.
PSEUDO_DMA - enables PSEUDO-DMA hardware, should give a 3-4X performance
increase compared to polled I/O.
PARITY - enable parity checking. Not supported
SCSI2 - enable support for SCSI-II tagged queueing. Untested
UNSAFE - leave interrupts enabled during pseudo-DMA transfers. You
only really want to use this if you're having a problem with
dropped characters during high speed communications, and even
then, you're going to be better off twiddling with transfersize.
USLEEP - enable support for devices that don't disconnect. Untested.
Common Problems :
1. Command timeouts, aborts, etc.
You should install the NCR5380 patches that I posted to the net
some time ago, which should be integrated into some future alpha
release. These patches fix a race condition in earlier NCR5380
driver cores, as well as fixing support for multiple devices on
NCR5380 based boards.
If that fails, you should disable the PSEUDO_DMA option by
changing the #define PSEUDO_DMA line in drivers/scsi/pas16.c to #undef
PSEUDO_DMA.
Note that the later should be considered a last resort, because
there will be a severe performance degradation.
Section 4.15 : Ultrastor 14f (ISA), 24f (EISA), 34f (VLB)
Ports : 0x130, 0x140, 0x210, 0x230, 0x240, 0x310, 0x330, 0x340
IRQs : 10, 11, 14, 15
DMA channels : 5, 6, 7
IO : port mapped, bus master
Autoprobe : does not work for boards at port 0x310, BIOS not required.
Autoprobe override : compile time only, define PORT_OVERRIDE
Common Problems :
1. The address 0x310 is not supported by the autoprobe code, and may
cause conflicts if networking is enabled.
Please use a different address.
2. Using an Ultrastor at address 0x330 may cause the system to hang
when the sound drivers are autoprobing.
Please use a different address.
3. Various other drivers do unsafe probes at various addresses, if you
are having problems with detection or the system is hanging at
boot time, please try a different address.
0x340 is recommended as an address that is known to work.
4. Linux detects no SCSI devices, but detects your SCSI hard disk
on an Ultrastor SCSI board as a normal hard disk, and the
hard disk driver refuses to support it. Note that when this
occurs, you will probably also get a message
hd.c: ST-506 interface disk with more than 16 heads detected,
probably due to non-standard sector translation. Giving up.
(disk %d: cyl=%d, sect=63, head=64)
If this is the case, you are running the Ultrastor board in
WD1003 emulation mode. You have
1. Switch the ultrastor into native mode. This is the
recommended action, since the SCSI driver can be
significantly faster than the IDE driver, especially with
the clustered read/write patches installed. Some users have
sustained in excess of 2M/sec through the file system using
these patches.
Note that this will be necessary if you wish to use any non-
hard disk, or more than two hard disk devices on the Ultrastor.
2. Use the kernel command line switch
hd=cylinders,heads,sectors
to override the default setting to bootstrap yourself,
keeping number of cylinders <= 2048, number of heads <= 16,
and number of sectors <= 255 such that cylinders * heads * sectors
is the same for both mappings.
You'll also have to manually specify the disk geometry when
running fdisk under Linux. Failure to do so will result in
incorrect partition entries being written, which will work
correctly with Linux but fail under MSDOS which looks at
the cylinder/head/sector entries in the table.
Once Linux is up, you can avoid the inconvience of having
to boot by hand by recompiling the kernel with an appropriately
defined HD_TYPE macro in include/linux/config.h.
Section 4.16 : Western Digital 7000
Supported Configurations :
BIOS Addresses : 0xce000
Ports : 0x350
IRQs : 15
DMA Channels : 6
IO : port mapped, bus master
Autoprobe : requires installed BIOS
Common Problems :
1. There are several revisisions of the chip and firmware. Supposedly,
revision 3 boards do not work, revision 5 boards do,
chips with no suffix do not work, chips with an 'A' suffix do.
2. The board supports a few BIOS addresses which aren't on the list
of supported addresses. If you run into this situation,
please use one of the supported addresses and submit a bug
report as outlined in Section 2, "Bug Reports"
Section 4.17 : AM53/79C974 (ALPHA)
ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/AM53C974-0.3.tar.gz
Supported Configurations :
Ports : all
IRQs : all
DMA Channels : 6
IO : port mapped, bus master (unintelligent)
Section 5 : Disks
This section gives information that is specific to disk drives.
Section 5.1 : Supported and Unsupported Hardware
All direct access SCSI devices with a block size of 256, 512, or
1024 bytes should work. Other block sizes will not work (Note
that this can often be fixed by changing the block and/or
sector sizes using the MODE SELECT SCSI command)
Sector size refers to the number of data bytes allocated per sector
on a device, ie CDROMs use a 2048 byte sector size.
Block size refers to the size of the logical blocks used to interface
with the device. Although this is usually identical to sector size,
some devices map multiple smaller physical sectors (ie, 256 bytes
in the case of 55M Syquest drives) to larger logical blocks or
vice versa (ie, 512 byte blocks on SUN compatable CDROM drives).
Removeable media devices, including Bernoulis, flopticals, and MO drives
work.
In theory, drives up to a terrabyte in size should work. There is
definately no problem with tiny 9G drives.
Section 5.2 : Common Problems
Section 5.2.1 : Cylinder > 1024 message.
When partitioning, you get a warning message about "cylinder > 1024"
or you are unable to boot from a partition including a logical
cylinder past logical cylinder 1024.
This is a BIOS limitation.
See Section 5.4 Disk Geometry and Partitioning for an explanation.
Section 5.2.2 : You are unable to partition "/dev/hd*"
/dev/hd* aren't SCSI devices, /dev/sd* are.
See Section 5.3, Device files, and Section 5.4, Disk
Geometry and Partitioning
for the correct device names and partitioning procedure.
Section 5.2.3 : Unable to eject media from a removeable media drive.
Linux attempts to lock the drive door when a piece of
media is mounted to prevent filesystem corruption due to
an inadvertant media change.
Please unmount your disks before ejecting them.
Section 5.2.4 : Unable to boot using LILO from a SCSI disk
In some cases, the SCSI driver and BIOS will disagree
over the correct BIOS mapping to use, and will result
in LILO hanging after 'LI' at boot time and/or
other problems.
To workarround this, you'll have to determine your BIOS
geometry mapping used under DOS, and make an entry for
your disk in /etc/lilo/disktab.
Alternatively, you may be able to use the "linear" configuration
file option.
Section 5.2.5 : Fdisk responds with
You must set heads sectors and cylinders.
You can do this from the extra functions menu.
and disk geometry is not 'remembered' when fdisk is rerun.
See Section 5.4 : Partitioning
Section 5.2.6 : Only one drive is detected on a bridge board with
multiple drives connected.
Linux won't search LUNs past zero on SCSI devices which
predate ANSI SCSI revision 1. If you wish devices on
alternate LUNs to be recognized, you will have to modify
drivers/scsi/scsi.c:scan_scsis().
Section 5.2.7 : System hangs when swapping
We think this has been fixed, try upgrading to 1.1.38.
Section 5.2.8 : Connor CFP1060S disks get corrupted
This is due to a microcode bug in the read-ahead and
caching code.
From Soenke Behrens of Conner tech. support :
During the past few weeks, we got several calls from customers stating
that they had severe problems with Conner CFP1060x 1GB SCSI drives
using the Linux operating system. Symptoms were corrupt filesystems
(damaged inodes) reported by e2fsck on each system boot and similar
errors.
There is now a fix available for customers with a CFP1060x (microcode
revisions 9WA1.62/1.66/1.68) and Linux. To apply the upgrade, you
will need a DOS boot disk and ASPI drivers that can access the hard
drive. The upgrade downloads new queuing and lookahead code into the
non-volatile SCSI RAM of the drive.
If you are experiencing problems with a disk that has microcode
revision 9WA1.60, you will have to contact your nearest Conner service
centre to get the disk upgraded. The microcode revision can be found
on the label of the drive and on the underside of the drive on a label
on one of the ICs.
If you are confident that you can perform the upgrade yourself, please
contact Conner Technical Support and have your microcode revision
ready. Conner Technical Support Europe can be reached on +44-1294-315333,
Conner Technical Support in the USA can be reached on 1-800-4CONNER.
Regards
Soenke Behrens
European Technical Support
Section 5.3 : Device Files
SCSI disks use block device major 8, and there are no "raw" devices
ala BSD.
16 minor numbers are allocated to each SCSI disk, with minor % 16 == 0
being the whole disk, minors 1 <= (minor % 16) <= 4 the four primary
partitions, minors 5 <= (minor % 16) <= 15 any extended partitions.
Ie, a configuration may work out like this (with one host adapter)
Device Target, Lun SCSI disk
84M Seagate 0 0 /dev/sda
SCSI->SMD bridge disk 0 3 0 /dev/sdb
SCSI->SMD bridge disk 1 3 1 /dev/sdc
Wangtek tape 4 0 none
213M Maxtor 6 0 /dev/sdd
Etc.
The standard naming convention is
/dev/sd{letter} for the entire disk device ((minor % 16) == 0)
/dev/sd{letter}{partition} for the partitions on that device
(1 <= (minor % 16) <= 15)
Ie
/dev/sda block device major 8 minor 0
/dev/sda1 block device major 8 minor 1
/dev/sda2 block device major 8 minor 2
/dev/sdb block device major 8 minor 16
etc.
Section 5.4 : Partitioning
You can partition your SCSI disks using the partitioning program
of your choice, under DOS, OS/2, Linux or any other operating
system supporting the standard partitioning scheme.
The correct way to run the Linux fdisk program is by specifying the
device on the command line. Ie, to partition the first SCSI disk,
fdisk /dev/sda
If you don't explicitly specify the device, the partitioning program
may default to /dev/hda, which isn't a SCSI disk.
In some cases, fdisk will respond with
You must set heads sectors and cylinders.
You can do this from the extra functions menu.
Command (m for help):
and/or give a message to the effect that the HDIO_REQ or
HDIO_GETGEO ioctl failed. In these cases, you must
manually specify the disk geometry as outlined in Subsection
5.5 : Disk Geometry when running fdisk, and also in /etc/disktab
if you wish to boot kernels off that disk with LILO.
If you have manually specified the disk geometry, subsequent
attempts to run fdisk will give the same error message. This
is normal, since PCs don't store the disk geometry information
in the partition table. In and of itself, will cause _NO PROBLEMS_,
and you will have no problems accessing partitions you created on
the drive with Linux. Some vendors' poor installation code will
choke on this, in which case you should contact your vendor
and insist that they fix the code.
In some cases, you will get a warning message about a partition ending
past cylinder 1024. If you create one of these partitions, you will
be unable to boot Linux kernels off of that partition using LILO. Note,
however, that this restriction does not preclude the creation of a
root partition partially or entirely above the 1024 cylinder mark,
since it is possible to create a small /boot partition below the
1024 cylinder mark or to boot kernels off existing partitions.
Section 5.5 : Disk Geometry
Under Linux, each disk is viewed as the SCSI host adapter sees it :
N blocks, numbered from 0 to N-1, all error free, where as DOS/BIOS
predate intelligent disks and apply an arbitrary head / cylinder /
sector mapping to this linear addressing.
This can pose a problem when you partition the drives under Linux,
since there is no portable way to get DOS/BIOS's idea of the mapped
geometry. In most cases, a HDIO_GETGEO ioctl() can be implemented
to return this mapping. Unfortunately, when the vendor (ie Seagate)
has chosen a perverse, non-standard, and undocumented mapping, this
is not possible and geometry must be manually specified
If manual specification of the is required, you have one of several
options :
1. If you don't care about using DOS, or booting kernels from the
drive with LILO, create a translation such that heads * cylinders *
sectors * 512 < size of your drive in bytes (a megabyte is defined
as 2^20 bytes).
1 <= heads <= 256
1 <= cylinders <= 1024
1 <= sectors <= 63
2. Use the BIOS mapping. In some cases, this will mean reconfiguring the
disk so that it is at SCSI ID 0, and disabling the second IDE drive (if you have one).
You can either use a program like NU, or you can use the following
program :
begin 664 dparam.com
MBAZ``##_B+^!`+N!`(H'0SP@=/D\,'5:@#]X=`6`/UAU4(!_`3AU2H!_`P!U
M1(I7`H#J,(#Z`7<Y@,*`M`C-$PCD=3-14HC()#\PY.@R`.@J`%J(\/[`,.3H
M)0#H'0!8AL2Q!M+L0.@7`+K"`;0)S2'#NIP!ZR"ZQ0'K&[K5`>L6N]T!,=*Y
M"@#W\8#",$N(%PG`=>^)VK0)S2'#=7-A9V4Z(&1P87)A;2`P>#@P#0H@("!O
L<B`@9'!A<F%M(#!X.#$-"B1);G9A;&ED(&1R:79E#0HD("`D```````D``!O
`
end
When run it prints the sectors, heads, and cylinders of the
drive whose BIOS address was specified on the command line (0x80
is the first disk, 0x81 the second).
Ie, dparam 0x80
60 17 1007
Would mean that C: had 60 sectors, 17 heads, and 1007 cylinders.
Section 6 : CD ROMs
This section gives information that is specific to cdrom drives.
Section 6.1 : Supported and Unsupported Hardware
SCSI CDs with a block size of 512 or 2048 bytes should work. Other
block sizes will not work.
Section 6.2 : Common Problems
Section 6.2.1 : Unable to mount cdrom.
The correct syntax to mount an ISO-9660 CDROM is
mount -t iso9660 /dev/sr0 /mount_point -o ro
Note that for this to work, you must have the kernel
configured with support for SCSI, your host adapter,
the SCSI CDROM driver, and the iso9660 filesystem.
Note that as of Linux 1.1.32, read-only devices such
as CDROMs CANNOT be mounted with the default read/write
options.
Section 6.2.2 : Unable to eject cdrom.
Linux attempts to lock the drive door when a piece of
media is mounted to prevent filesystem corruption due to
an inadvertant media change.
Section 6.2.3 : Unable to play audio.
The programs Workman or xcdplayer will do this for you.
Section 6.2.4 : Workman or Xcdplayer do not work.
The functions to control audio functions are part of the
SCSI-II command set, so any drive that is not SCSI-II will probably
not work here. Also, many SCSI-I and some SCSI-II CDROM drives use a
proprietary command set for accessing audio functions instead of the
SCSI-II command set. For NEC drives, there is a version of xcdplayer
specially adapted to use this command set floating around - try
looking on tsx-11.mit.edu in pub/linux/BETA/cdrom.
These programs may work with some of the non-SCSI cdrom drives
if the driver implements the same ioctls as the scsi drivers.
Section 6.2.5: Additional drives on CD ROM changers do not work
Most CD changers assign each disc to a logical unit. Insure that
you have special files made for each platter (see Section 6.3 : Device Files)
and see Section 1.10 : LUNS other than 0 don't work
Section 6.3 : Device Files
SCSI CD ROMs use major 11.
Minors are allocated dynamically (See Section 5 : Disks, Subsection 5.3 :
Device Files for an example) with the first CDROM found being minor 0,
the second minor 1, etc.
The standard naming convention is
/dev/sr{digit}, although some distributions have used /dev/scd{digit}, with
examples being
/dev/sr0 /dev/scd0
/dev/sr1 /dev/scd1
Section 7 : Tapes
This setion gives information that is specific to scsi tape drives.
Section 7.1 : Supported and Unsupported Hardware
Drives using both fixed and variable length blocks smaller than the
the driver buffer length (set to 32K in the distribution sources) are
supported.
Parameters (block size, buffering, density) are set with ioctls
(usually with the mt program), and remain in effect after the
device is closed and reopened.
Virtually all drives should work, including :
Archive Viper QIC drives, including the 150M and 525M models
Exabyte 8mm drives
Wangtek 5150S drives
Wangdat DAT drives
Section 7.2 : Common Problems
Section 7.2.1 : Tape drive not recognized at boot time.
Try booting with a tape in the drive.
Section 7.2.2 : Tapes with multiple files cannot be read properly.
When reading a tape with multiple files, the first tar
is successful, a second tar fails silently, and retrying
the second tar is successful.
User level programs, such as tar, don't understand file marks.
The first tar reads up until the end of the file. The second
tar attempts to read at the file mark, gets nothing, but the
tape spaces over the file mark. The third tar is successful
since the tape is at the start of the next file.
Use mt on the no-rewind device to space forward to the next file.
Section 7.2.3 : Decompression fails.
Decompressing programs cannot handle the zeros padding the
last block of the file.
To prevent warnings and errors, wrap your compressed files
in a .tar file - ie, rather than doing
tar cfvz /dev/nrst0 file.1 file.2 ...
do
tar cfvz tmp.tar.z file.1 file.2 ...
tar cf /dev/nrst0 tmp.tar.z
Section 7.2.4 : Problems taking tapes to/from other systems.
You can't read a tape made with another operating system or
another operating system can't read a tape written in Linux.
Different systems often use different block sizes. On a
tape device using a fixed blocksize, you will get errors
when reading blocks written using a different block size.
To read these tapes, you must set the blocksize of
the tape driver to match the blocksize used when
the tape was written, or to variable.
NOTE : this is the hardware block size, not the blocking
factor used with tar, dump, etc.
You can do this with the mt command -
mt setblk <size>
or
mt setblk 0
to get variable block length support.
Note that these mt flags are NOT supported under the GNU version
of mt which is included with some Linux distributions. Instead,
you must use the BSD derrived Linux SCSI mt command. Source
should be available from
tsx-11.mit.edu:/pub/linux/ALPHA/scsi
Section 7.2.5 : "No such device" error message.
All attempts to access the tape result in a
"No such device"
or similar error message. Check the type of
your tape device - it MUST be a character device with
major and minor numbers matching those specified in subsection
C, Device Files.
Section 7.2.6 : Tape reads at a given density work, writes fail
Many tape drives support reading at lower densities
for compatability with older harware, but will not
write at those same densities.
This is especially the case with QIC drives, which
will read old 60M tapes but only write new 120, 150,
250, and 525M formats.
Section 7.2.6 : Repositioning the tape locks out access to all SCSI devices
This is most common with SCSI drivers which only support one
outstanding command at a time (see Section 9.5 : Multiple
devices for an explanation, and Section : Driver feature comparison
to see which drivers suffer from this limitation), although there may
be a few tape drives out there which refuse to disconnect.
In either case, you can work arround the problem by editing
drivers/scsi/st.c and adding a
#define ST_NOWAIT
at the top and rebuilding the kernel.
Note that this will defer error condition reporting until the
next SCSI command is executed. For this reason, you may want to
do something like a
mt status
after a mt file positioning command so you don't overwrite tape
files if the positioning command failed.
You may also wish to consider changing to a better-supported SCSI
board or newer tape drive if you need to use this workarround
and are writing multiple files to tapes.
Section 7.3 : Device Files
SCSI tapes use character device major 9.
Due to constraints imposed by Linux's use of a sixteen bit dev_t with
only eight bits allocated to the minor number, the SCSI tape minor
numbers are assigned dynamically starting with the lowest SCSI HOST/ID/LUN.
Rewinding devices are numbered from 0 - with the first
SCSI tape, /dev/rst0 being c 9 0, the second /dev/rst1 c 9 1, etc.
Non-rewinding devices have the high bit set in the minor number,
ie /dev/nrst0 is c 9 128.
The standard naming convention is
/dev/nrst{digit} for non-rewinding devices
/dev/rst{digit} for rewinding devices
Section 8 : Generic
This information gives information that is specific to the generic
scsi driver.
Section 8.1 : Supported Hardware
The Generic SCSI device driver provides an interface for sending
SCSI commands to all SCSI devices - disks, tapes, CDROMs, media
changer robots, etc.
Everything electrically compatable with your SCSI board should work.
Section 8.2 : Common Problems
None :-).
Section 8.3 : Device Files
SCSI generic devices use character major 21. Due to constraints
imposed by Linux's use of a 16 bit dev_t, minor numbers are dynamically
assigned from 0, one per device, with
/dev/sg0
corresponding to the lowest numerical target/lun on the first
SCSI board.
Section 9 : Buyers' Guide
A frequent question is:
"Linux supports quite a number of different boards, so which
scsi host adapter should I get."
The answer depends upon how much performance you expect or need,
motherboard, and the scsi peripherals that you plan on attaching to
your machine.
Section 9.1 : Transfer types
The biggest factor affecting performance (in terms of throughput
and interactive response time during SCSI I/O) is the transfer type used.
The table below lists the various transfer types, the effects they have
on performance, and some recomendations as to their use.
Transfer type Description / Performance / Recomendedations
Pure A pure polled I/O board will use the CPU to handle
Polled all of the SCSI processing, including the REQ/ACK
handshaking.
Even a fast CPU will be slower handling the REQ/ACK
handshake sequence than a simple finite state machine,
resulting in peak transfer rates of about 150K/sec on
a fast machine, perhaps 60K/sec on a slow machine
(through the filesystem).
The driver also must sit in a tight loop as long as the
SCSI bus is busy, resulting in near 100% CPU utilitization
and extremely poor responsiveness during SCSI I/O.
Slow CDROMs which don't disconnect/reconnect will kill
interactive performance with these boards.
Not recommended.
Interlocked Boards using interlocked polled I/O are essentially
Polled the same as pure polled I/O boards, only the SCSI REQ/ACK
handshaking signals are interlocked with the PC bus
handshaking signals. All SCSI processing beyond
the handshaking is handled by the CPU.
Peak transfer rates of 500-600K/sec through the
filesystem are possible on these boards.
As with pure polled I/O boards, the driver must sit
in a tight loop as long as the SCSI bus is busy,
resulting in CPU utilization dependant on the
transfer rates of the devices, and when they
disconnect/reconnect. CPU utilization may vary
between 25% for single speed CDs which handle
disconnect/reconnect properly to 100% for faster
drives or broken CD ROMs which fail to disconnect/reconnect.
On my 486-66, with a T128, I use 90% of my CPU time to
sustain a throughput of 547K/sec on a drive
with a headrate of 1080K/sec with a T128 board.
Sometimes acceptable for slow tapes and CDROMs when
low cost is essential.
FIFO Boards using FIFO polled I/O put a small (typically 8K)
Polled buffer between the CPU and the SCSI bus, and often implement
some amount of intelligence. The net effect is that
the CPU is only tied up when it is transfering data
at top speed to the FIFO and when it's handling the
rest of the interrupt processing for FIFO empty conditions,
disconnect/reconnect, etc.
Peak transfer rates should be sufficient to handle
most SCSI devices, and have been measured at up
to 4M/sec using raw SCSI commands to read 64K
blocks on a fast Seagate Barcuda with an Adaptec
1520.
CPU utilization is dependant on the transfer
rates of the devices, with faster devices generating
more interrupts per unit time which require more CPU
processing time. Although CPU usage may be high
(perhaps 75%) with fast devices, the system usually
remains usable. These boards will provide excellent
interactive performance with broken devices which
don't disconnect/reconnect (typically cheap CDROM
drives)
Recommended for persons on a budget.
Slave Drivers for boards using slave DMA program the PC's
DMA DMA controller for a channel when they do a data transfer,
and return control to the CPU.
Peak transfer rates are usually handicapped
by the poor DMA controller used on PCs,
with one such 8-bit board having problems
going faster than 140-150K/sec with one mainboard.
CPU utilization is very reasonable, slightly
less than what is seen with FIFO polled I/O boards.
These boards are very tollerant of broken devices
which don't disconnect/reconnect (typically cheap
CSG limitDROM drives).
Acceptable for slow CDROM drives, tapes, etc.
Busmastering These boards are intelligent. Drivers
DMA for these boards throw a SCSI command, the destination
target and lun, and where the data should end up
in a structure, and tell the board "Hey, I have
a command for you." The driver returns control
to various running programs, and eventually the
SCSI board gets back and says that it's done.
Since the intelligence is in the host adapter
firmware and not the driver, drivers for these
boards typically support more features - synchronous
transfers, tagged queing, etc.
With the clustered read/write patches, peak transfer
rates through the file system approach 100% of head rate
writing, 75% reading.
CPU utilization is minimal, irregardless of
I/O load, with a measured 5% CPU usage while
accessing a double speed CDROM on an Adaptec 1540
and 20% while sustaining a 1.2M/sec transfer rate
on a SCSI disk.
Recommended in all cases where money is not extremely
tight, the main board is not broken (some broken main boards
do not work with bus masters), and applications where time
to data is more important than throughput are not being run
(bus master overhead may hit 3-4ms per command).
Section 9.2 : Scatter/gather
The second most important driver/hardware feature with respect
to performance is support for scatter/gather I/O. The overhead of executing
a SCSI command is significant - on the order of milliseconds. Intelligent bus
masters like the Adaptec 1540 may take 3-4ms to process a SCSI command before
the target even sees it. On unbuffered devices, this overhead is allways enough
to slip a revolution, resulting in a transfer rate of about 60K/sec
(assuming a 3600RPM drive) per block transfered at a time. So, to maximize
performance, it is necessary to minimize the number of SCSI commands needed
to transfer a given amount of data by transfering more data per command. Due
to the design of the Linux buffer cache, contiguous disk blocks are not
contiguous in memory. With the clustered read/write patches, 4K worth of
buffers are contiguous. So, the maximum amount of data which can
be transfered per SCSI command is going to be 1K * # of scatter/gather
regions without the clustered read/write patches, 4K * # of regions
with. Experimentally, we've determined that 64K is a reasonable
amount to transfer with a single SCSI command - meaning 64 scatter/gather
buffers with clustered read/write patches, 16 without. With the
change from 16K to 64K transfers, we saw an improvement from
50% of headreate, through the filesystem, reading and writing,
to 75% and 100% respectively using an Adaptec 1540 series board.
Section 9.3 : Mailbox vs. non-mailbox
A number of intelligent host adapters, such as the Ultrastor, WD7000,
Adaptec 1540, 1740, and Buslogic boards have used a mailbox-metaphor
interface, where SCSI commands are executed by putting a SCSI command
structure in a fixed memory location (mailbox), signaling the board (ie,
raising the outgoing mail flag), and waiting for a return (incoming mail).
With this high level programming interface, users can often upgrade to a
newer board revision to take advantage of new features, such as FAST +
WIDE SCSI, without software changes. Drivers tend to be simpler to
implement, may implement a larger feature set, and may be more stable.
Other intelligent host adapters, such as the NCR53c7/8xx family,
and Adaptec AIC-7770/7870 chips (including the 274x, 284x, and 2940
boards) use a lower level programming interface. This may prove
faster since processing can be shifted between the board's processor
and faster host CPU, allow better flexibility in implementing certain
features (ie, target mode for arbitrary devices), and these boards
can be built for less money (In some cases, this is passed on to
the consumer (ie, most NCR boards)). On the down side, drivers
tend to be more complex, and must be modified to take advantage of
the features present on newer chips.
Section 9.4 : Bus types
Bus type is the next thing to consider, with choices including ISA,
EISA, VESA, and PCI. Marketing types often spout of absurd bandwidth
numbers based on burst transfer rates and fiction, which isn't very
useful. Instead, I've chosen to state "real-world" numbers based on
measured performance with various peripherials.
Bus Bandwidth, description,
ISA Bandwidth is slightly better than 5M/sec for busmastering
devices. With an ISA bus, arbitration for busmasters is performed
by the venerable 8237 third party DMA controller, resulting in
relatively high bus aquisition times. Interrupt drivers are
tri-state and edge triggered, meaning interrupts cannot be
shared. Generally, ISA is unbuffered, meaning the host/memory
bus is tied up whenever a transfer is occuring. No mechanism
is provided to prevent bus-hogging.
VESA Bandwidth is about 30M/sec. Some VESA systems run the bus out
of spec, rendering them incompatable with some boards, so this
should be taken into consideration before purchasing hardware
without a return guarantee. Generally, VESA is unbuffered, meaning
meaning the host/memory bus is tied up whenever a transfer is
occuring.
EISA Bandwidth is about 30M/sec, with busmastering operations generally
being faster than VESA. Some EISA systems buffer the bus, allowing
burst transfers to the faster host/memory bus and minimizing impact
on CPU performance. EISA interrupt drivers may be either tri-state
edge-triggered or open collector level-active, allowing interrupt
sharing with drivers that support it. Since EISA allocates a
separate address space for each board, it is usually less prone to
resource conflicts than ISA or VESA.
PCI Bandwidth is about 60M/sec. Most PCI systems implement write
posting buffers on the host bridge, allowing speed mismatches
on either side to have a minimum impact on bus/CPU performance.
PCI interrupt drivers are open collector level-active, allowing
interrupt sharing with drivers that support it. Mechanisms
are provided to prevent bus hogging, and for both master and
slave to suspend a bus-mastering operation.
Since PCI provides a plug-n-play mechanism with writeable
configuration registers on every board, in a separate address space,
a propperly implemented PCI system is plug-and play.
PCI is extremely strict as to trace length, loading, mechanical
specifications, etc. and ultimately should be more reliable than
VESA or ISA.
In summary, PCI is the best PC bus, although it does
have its dark side. PCI is still in its infancy, and although
most manufacturers have ironed out the problems, there is
still stock of older, buggy PCI hardware and broken main
BIOSes. For this reason, I _strongly_ recommend a return
guarantee on the hardware. While the latest PCI mainboards
are truly plug-and-play, older PCI boards may require the
user to set options with both jumpers and in software (ie,
interrupt assignments). Although many users have
resolved their PCI problems, it has taken time and for this
reason I cannot recommend a PCI purchase if having the
system operational is extremely time critical.
For many slower SCSI devices, such as disks with head rates
arround 2M/sec or less, CDROMs, and tapes, there will be little difference
in throughputs with the different PC bus interfaces. For faster contemporary
SCSI drives (Typical high end multi-gigabyte drives have a head rate of
4-5M/sec, and at least one company is currently ALPHA testing a parallel
head unit with a 14M/sec head rate), throughput will often be significantly
better with controllers on faster busses, with one user noting a 2.5 fold
performance improvement when going from an Adaptec 1542 ISA board to a
NCR53c810 PCI board.
With the exception of situations where PCI write-posting or a
similar write-buffering mechanism is being used, when one of the busses in
your system is busy, all of the busses will be unaccessable. So, although
bus saturation may not be interfering with SCSI performance, it may have a
negative effect on interactive performance. Ie, if you have a 4M/sec SCSI
disk under ISA, you'll have lost 80% of your bandwidth, and in an
ISA/VESA system would only be able to bitblt at 6M/sec. In most cases,
a similar impact on processing jobs in the background would also be felt.
Note that having over 16M of memory does not preclude using
an ISA busmastering SCSI board. Unlike various broken operating
systems, Linux will double buffer when using a DMA with an ISA controller
and a transfer is ultimately destined for an area above 16M. Performance
on these transfers only suffers by about 1.5%, ie not noticably.
Finally, the price difference between bus masters offered with the
different bus interfaces is often minimal.
With all that in mind, based on your priorities you will have
certain bus preferences
Stability, time critical installations, EISA ISA VESA PCI
and poor return policies
Performance, and typical hobbiest PCI EISA VESA ISA
installations
As I pointed out earlier, bus mastering versus other transfer modes is
going to have a bigger impact on total system performance, and should be
considered more important than bus type when purchasing a SCSI controller.
Section 9.5 : Multiple devices
If will you have multiple devices on your SCSI bus, you may
want to see whether the host adapter/driver that you are considering supports
more than one outstanding command at one time. This is almost
essential if you'll be running a tape drive, and very desireable
if you are mixing devices of different speeds, like a CD ROM and a disk
drive. If the linux driver only supports one outstanding command, you may
be locked out of your disk drive while a tape in the tape drive is rewinding or
seeking to end of media (perhaps for half an hour). With two
disk drives, the problem will not be as noticeable, allthough
throughput would approach the average of the two transfer rates
rather than the sum of the two transfer rates.
Section 9.6: SCSI-I, SCSI-II, SCSI-III FAST and WIDE options, etc.
Over the years, SCSI has evolved, with new revisions of the standard
introducing higher transfer rates, methods to increase throughput, standardized
commands for new devices, and new commands for previously supported devices.
In and of themselves, the revision levels don't really mean anything.
Excepting minor things like SCSI-II not allowing the single initiator option
of SCSI-I, SCSI is backwards compatable, with new features being introduced
as options and not mandatory. So, the descision to call a SCSI adapter
SCSI, SCSI-II, or SCSI-III is almost entirely a marketing one.
Section 9.7 : Driver feature comparison
Driver feature comparison (supported chips are listed in parenthesis)
Driver Simultaneous SG > 1
Transfer mode Commands limit Boards
total/LUN
AM53C974 Busmastering DMA 12s/1s 255s Y
aha152x FIFO(8k) Polled 7s/1s 255s N
(AIC6260,
AIC6360)
aha1542 Busmastering DMA 8s/1s 16 Y
aha1740 Busmastering DMA 32s 16 N
aha274x Busmastering DMA 4s/1s 255s Y
buslogic Busmastering DMA Y 64s, 8196h Y
eata_dma Busmastering DMA 64s/16s 64s Y
fdomain FIFO(8k) Polled 1s 64s N
(TMC1800, except TMC18c30
TMC18c30, with 2k FIFO
TMC18c50,
TMC36c70)
in2000* FIFO(2k) Polled 1s 255s N
g_NCR5380 Pure Polled 16s/2s 255s Y
(NCR5380,
NCR53c80,
NCR5381,
NCR53c400)
gsi8* Slave DMA 16s/2s 255s
(NCR5380)
PAS16 Pure Polled 16s/2s 255s Y
(NCR5380) or Interlocked Polled
(fails on some systems!)
seagate Interlocked Polled 1s/1s 255s N
wd7000 Busmastering DMA 16s/1s 16 Y
t128 Interlocked Polled 16s 255s Y
(NCR5380)
qlogic Interlocked Polled 1s/1s 255s N
ultrastor Busmastering DMA 16s/2s 32 Y
53c7,8xx Busmastering DMA
(NCR53c810,
NCR53c815,
NCR53c820,
NCR53c825)
rel5 1s/1s 127s N
rel10 8s/1s 127s Y
Notes :
1. drivers flagged with an '*' are not included with the
distribution kernel, and binary boot images may be unavailable.
2. numbers suffixed with an 's' are arbitrary limits set in software
which may be changed with a compile time define.
3. hardware limits are indicated by an 'h' suffix, and may differ
from the software limits currently imposed by the Linux drivers.
4. unsuffixed numbers may indicate either hard or soft limits.
5. rel5 of the NCR53c810 driver is included in the stock 1.2.x and
1.3.x kernels; rel10 is available via anonymous FTP.
6. With the exception of the AM53C974, the busmastering DMA boards
are intelligent; with the NCR executing microcode from main memory,
the AIC7770 executing microcode from on-chip RAM, and the rest using
a mailbox-style interface.
Section 9.8 : Board comparison
Board Driver Bus Price Notes
Adaptec AIC-6260 aha152x ISA chip, not board
Adaptec AIC-6360 aha152x VLB chip, not board
(Used in most
VESA/ISA multi-IO
boards with SCSI,
Zenon mainboards)
Adaptec 1520 aha152x ISA
Adaptec 1522 aha152x ISA $80 1520 w/FDC
Adaptec 1510 aha152x ISA 1520 w/out boot ROM,
won't autoprobe.
Adaptec 1540C aha1542 ISA
Adaptec 1542C aha1542 ISA 1540C w/FDC
Adaptec 1540CF aha1542 ISA FAST SCSI-II
Adaptec 1542CF aha1542 ISA $200 1540CF w/FDC
Adaptec 1640 aha1542 MCA
Adaptec 1740 aha1740 EISA discontinued
Adaptec 1742 aha1740 EISA discontinued, 1740
w/FDC
Adaptec 2740 aha274x EISA
Adaptec 2742 aha274x EISA w/FDC
Adaptec 2840 aha274x VLB
Adaptec 2842 aha274x VLB w/FDC
Adaptec 2940 aha274x PCI
Allways IN2000 in2000 ISA
Buslogic 445S aha1542, VLB $250 FAST SCSI-II, active
buslogic termination, w/FDC
Buslogic 747S aha1542, EISA FAST SCSI-II, active
buslogic termination, w/FDC
Buslogic 946S buslogic PCI FAST SCSI-II, active
termination.
Buslogic 956C buslogic PCI WIDE version of 946
DPT PM2011 eata_dma ISA FAST SCSI-II
PM2012A eata_dma EISA FAST SCSI-II
PM2012B eata_dma EISA FAST SCSI-II
PM2021 eata_dma ISA $245 FAST SCSI-II
PM2022 eata_dma EISA $449 FAST SCSI-II
active termination
PM2024 eata_dma PCI $395 FAST SCSI-II
active termination
PM2122 eata_dma EISA $595 FAST SCSI-II
active termination
PM2124 eata_dma PCI $595 FAST SCSI-II
active termination
PM2322 eata_dma EISA FAST SCSI-II
active termination
PM3021 eata_dma ISA $1595 FAST SCSI-II
multichannel
raid/simm sockets
active termination
PM3122 eata_dma EISA $1795 FAST SCSI-II
multichannel/raid
active termination
PM3222 eata_dma EISA $1795 FAST SCSI-II
multichannel
raid/simm sockets
active termination
PM3224 eata_dma PCI $1995 FAST SCSI-II
multichannel
raid/simm sockets
active termination
DTC 3290 aha1542 EISA Although it should work,
due to documentation
release polcies, DTC
hardware is unsupported
DTC 3292 aha1542 EISA 3290 w/FDC
DTC 3292 aha1542 EISA 3290 w/FDC
Future Domain 1680 fdomain ISA FDC
Future Domain 3260 fdomain PCI
NCR53c810 (boards sold 53c7,8xx PCI $60 chip, not board. Boards
by FIC, Chaintech, (board) don't include
Nextor, Gigabyte, etc. BIOS, although most
Mainboards with chip by non-NCR equipped main
AMI, ASUS, J-Bond, boards have the SDMS
etc. Common in DEC BIOS
PCI systems)
NCR53c815 ( 53c7,8xx PCI $100 NCR53c810 plus
Intel PCISCSIKIT, bios
NCR8150S, etc)
NCR53c825 53c7,8xx PCI $120 Wide variant of
NCR53c815. Note that
the current Linux
driver does not
negotiate for wide
transfers.
Pro Audio Spectrum 16 pas16 ISA Sound board w/SCSI
Seagate ST01 seagate ISA $20 BIOS only works with
some drives
Seagate ST02 seagate ISA $40 ST01 w/FDC
Sound Blaster 16 SCSI aha152x ISA Sound board w/SCSI
Western Digital 7000 wd7000 ISA w/FDC
Trantor T128 t128 ISA
Trantor T128F t128 ISA T128 w/FDC and
support for high IRQs
Trantor T130B g_NCR5380 ISA
Ultrastor 14F ultrastor ISA w/FDC
Ultrastor 24F ultrastor EISA w/FDC
Ultrastor 34F ultrastor VLB
Notes :
1. Trantor was recently purchased by Adaptec, and some products are being
sold under the Adaptec name.
2. Ultrastor recently filed for Chapter 11 Bankruptcy, so technical
support is non-existant at this time.
3. Various Buslogic boards other than the 545S, 445S, 747S, and
946S _should_ work, although to my knowledge have not been
tried.
4. The price for the busmastering NCR53c810 boards is not
a typo, includes the standard ASPI/CAM driver package for
DOS, OS/2 and Windows (32 bit access), and other drivers are
available for free download.
If you can't find one at that price, I would strongly suggest that
you peruse Computer Shopper - I've seen '810 boards in there for
$60, and '825 boards for $120. If you refuse to do that, some people
have had luck with the following companies :
InteliSys at (703) 385-0347
Superpower at (800) 736-0007
SW (swt@netcom.com) (214) 907-0871 fax (214) 907-9339
Insight Electronics (609) 985-5556
5. Adaptec's recent SCSI chips show an unusual sensitivity
to cabling and termination problems. For this reason,
I cannot recommend the Adaptec 154x C and CF revisions or the
2xxx series.
Note that the reliability problems do not apply to the
older 154x B revision boards, 174x A revision boards,
or to my knowledge AIC-6360/AIC-6260 based boards (1505, 1510,
1520, etc).
Also, the quality of their technical support has slipped markedly, with
long delays becoming more common, and their employees being ignorant
(suggesting there were non-disclosure policies affecting certain
literature when there were none), and hostile (ie, refusing to pass
questions on to some one else when they couldn't answer them).
If users desire handholding, or wish to make a political statement,
they should take this point into consideration. Otherwise, the
Adaptec 152x/1510/1505 are nicer than the other ISA boards in the
same price range, and there are some excellent deals on used and
surplus 154x B revision boards and 1742 boards which IMHO outweigh
the support problems.
6. All given prices for the DPT controllers are official list prices.
Street prices should be considerably lower.
All boards can be upgraded with cache and raid modules, most of the
boards are also available in Wide and/or Differential versions.
Section 9.9 : Summary
Most ISA, EISA, and VESA users will probably be served best by
a Buslogic board, due to its performance, features such as active termination,
and Adaptec 1540 compatability. There are a number of models available with
EISA, ISA, PCI, and VESA local bus interfaces, in single ended and differential,
and 8/16 bit SCSI bus widths.
People with PCI systems should consider NCR53c810 based boards. These
are bus mastering SCSI controllers, available in quantity one for about $60
(ie, cheaper than the Adaptec 1520). In addition to being the cheapest PCI
SCSI boards, the NCR boards were also benchmarked as faster than the
Adaptec 2940 and Buslogic BT-946, and demonstrate excellent performance under
Linux (up to 4M/sec through the file system ). The disadvantages of these
boards versus the Buslogics are that they aren't Adaptec 1540 compatable,
may or may not come with active termination, and you'll need the alpha code
from tsx-11 to make full use of the hardware.
People wanting non-PCI SCSI on a limited budget will probably be
happiest finding a surplus or used Adaptec 154x B revision or 174x A
revision, or an Adaptec 1520 clone of some sort (about $80) if they want
new hardware. These boards offer reasonable throughput and interactive
performance at a modest price.
Section 10 : Assignment of minor numbers
Due to constraints imposed by Linux's use of a sixteen bit dev_t with
only eight bits allocated to the minor number, SCSI disk, tape,
CDROM, and generic minor numbers are assigned dynamically.
iaccording to the following procedure :
For all SCSI host adapters, from scsi0 through scsiN
For all SCSI IDs on this bus, from 0 through 7, except for
this host adapter's ID
For all logical units, from 0 through max_scsi_luns
- Probe the bus, target, and LUN combination by
issuing a TEST UNIT READY command. If we don't
think a unit was here, don't probe any more LUNs
on this bus + SCSI ID.
- Send an INQUIRY command to determine what we've
found; including the device type, vendor, model,
firmware revision, etc.
- Pass the results of this to a special recognition
function for each high level driver present (i.e. disk,
tape, etc). Attach this device to the next available
unit for any drivers that are willing to drive this.
The generic device will attach to all devices.
- If it was SCSI-I, or in a list of devices known
not to handle multiple LUNs, don't probe any more
LUNs on this bus + SCSI ID.
- If it is a device known to have multiple LUNs, then
a scan of the full LUN spectrum is forced, overriding
max_scsi_luns.
There are frequently problems with this approach because if you have a
system where some devices are only present some of the time, then the
minor numbers for a given device will depend upon which devices were
present at boot time. This can present problem, because rc scripts or
the file /etc/fstab might contain instructions for mounting specific
partitions which fails when the disk appears with a different minor
number.
This problem has not yet been fully solved. There is a
program which can be found on tsx-11 that creates a /dev/scsi heirarchy
based upon host number, id and lun. This is a bit clumsy, but it would
help to alleviate some of the problems.
A better solution will probably come out of the /proc/scsi pseudo
directory. This is currently a work in progress, so at present we cannot
say exactly the form of the solution, but at the time of this writing
this appears to be a promising approach for resolving some of these
issues.
EOF