\i0 support the use of non-NeXT disks as the internal disk of a system. Even though a disk might work fine as an external drive, unless it is a disk sold by NeXT we cannot necessarily support its use as an internal drive.\
Termination issues are covered in Appendix B of the User Reference manual. Basically, the last drive of an external “chain” of drives should be terminated; all other “intermediate” external drives should be unterminated. Check the drive manufacturer's documentation regarding termination. Note also that power for SCSI termination should be from the SCSI bus, rather than internally supplied.\
\
The main rules to remember when selecting the SCSI target number are: it must be unique — no other device can share the same target number — and it should be higher than any pre-existing disk device. The best target number to use is the next available target number after all pre-existing disks. (See NextAnswer hardware.412 for information on SCSI target numbers. Search in the Digital Librarian for “scsi target.”).\
\
Once you have your disk configured, power down your NeXT machine and cable the disk to your system using an appropriate SCSI cable. Especially if you have many external SCSI devices (i.e., more than one), or if you have long cables, you should be sure the impedance of the cable is correct (100
\f4 W
\f0
\f4 –
\f0 10
\f4 W
\f0 ). Then power-up the disk, followed by the NeXT machine.\
\
(If you'd like to check your configuration, manually boot your machine and look at the configuration info printed as the machine boots up Mach. You should see something like this:\
\
\f2\fs20 SCSI 53C90 Controller,....\
MAXTOR XT-8360S as sd0 at sc0 target 0 lun 0\
Disk Label: Something....\
Disk Capacity: 660MB, Device Block 1024 bytes\
YOUR NEW DISK VENDOR AND MODEL as sd1 at sc0 target 1\
sd1: Can't read label\
\
\f0\fs28 The error on reading the label is expected, since the disk hasn't been initialized.)\
\
2. Once you have rebooted your machine, login as root. You now need to “initialize” the new disk.
\i Be careful
\i0 as you do this; the commands involved are
\b dangerous
\b0 to the data on your other disks if you mistype something!\
\
Disks are initialized with the
\f1\fs24 disk
\f0\fs28 (8) command (located in
\f1\fs24 /usr/etc/disk
\f0\fs28 .) The
\f1\fs24 disk
\f0\fs28 command determines how to initialize your disk by finding a description of the disk in
\f1\fs24 /etc/disktab
\f0\fs28 (see the
\f1\fs24 disktab
\f0\fs28 (5) man page for a description of the file), or by using defaults it can determine from most disks. Only certain disks are described in
\f1\fs24 disktab
\f0\fs28 ; if your's isn't there, and if the command cannot read the appropriate information from the disk, you'll have to add a new entry describing your disk. See the UNIX Manual Pages for details.\
\
To initialize the disk, use the following command (this assumes the new disk is disk 1, as shown above; substitute the appropriate disk number if this is not the case; also, note that
\f1\fs24 Courier font
\f0\fs28 is used to denote computer output, and
\f1\b\fs24 Courier Bold
\f0\b0\fs28 is user to show user input):\
\
\f1\fs24 rhino#
\b disk -i /dev/rsd1a
\b0 \
\f0\fs28 \
\i Specify the device
\i0 (
\f1\fs24 /dev/rsd1a
\f0\fs28 )
\i\ul VERY
\ul0 CAREFULLY!
\i0 Specifying the wrong device will destroy data. The example shown here is for the disk device that has the
\i second
\i0 target number. To clarify, here's an example table that matches /dev names to target numbers. The key thing is that “sd”
\f1\fs24 /dev
\f0\fs28 names are assigned sequentially, at boot time, to each increasing disk target number.\
\
\b Target
\f1\fs24 /dev
\f0\fs28 name\
\b0 1
\f1\fs24 /dev/rsd0a
\f0\fs28 \
3
\f1\fs24 /dev/rsd1a
\f0\fs28 \
4
\f1\fs24 /dev/rsd2a
\f0\fs28 \
6
\f1\fs24 /dev/rsd3a
\f0\fs28 \
\
\f1\fs24 /dev
\f0\fs28 names are always sequential with no gaps, even if the target numbers have gaps. (Note some of the gaps in the target numbers could be due to other device types; e.g., you could have a tape drive as target 1 in the example above.) Note that if you disconnected target 1, then target 3 would be known as
\f1\fs24 /dev/rsd0a
\f0\fs28 .\
\
If
\f1\fs24 disk
\f0\fs28 can't find the disktab entry and if it cannot determine the necessary information (the drive geometry) from the disk, you need to create one. The (undocumented)
\f1\fs24 scsimodes
\f0\fs28 command will garner most of the information you need, besides the partition layout:\
\
\f1\fs24 #
\b scsimodes /dev/rsd0a
\b0 \
SCSI information for /dev/rsd0a\
Drive type: MAXTOR XT-8760S\
512 bytes per sector\
53 sectors per track\
15 tracks per cylinder\
1632 cylinder per volume (including spare cylinders)\
1 spare sectors per track\
45 alternate tracks per volume\
1268279 usable sectors on volume\
\f0\fs28 \
Unfortunately, in at least most of the cases where
\f1\fs24 disk
\f0\fs28 cannot determine the drive geometry,
\f1\fs24 scsimodes
\f0\fs28 won't be able to, either. You'll have to get the drive geometry from the documentation accompanying the drive, or from the drive manufacturer.\
\
Use an editor to modify
\f1\fs24 /etc/disktab
\f0\fs28 to create a new disktab by hand. Note that this is
\b not
\b0 a trivial procedure, nor is it particularly supported. Your support organization will assist to the best of its abilities, but we do not guarantee anything. Again, this is unsupported.\
\
3. Once you have the disk initialized; you need to modify the UNIX file
\f1\fs24 /etc/fstab
\f0\fs28 . Probably the simplest thing to do is copy an existing mount entry and edit it. You can always mount the device manually (see
\f1\fs24 mount
\f0\fs28 (8)) for a trial run. You may add the device to the NetInfo
\b /mounts
\b0 directory, though this is not needed because local disks are mounted before starting NetInfo.\
