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7_ Storage.txt
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1996-04-17
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Subject: FAQ: 7 - Storage
7 STORAGE
7.1 Disktab help needed: ST15230N
disktab ST15230N Seagate, ST15230
This is the /etc/disktab entry for the SEAGATE ST15230N.
ST15230N_1024|SEAGATE ST15230N_1024:\
:ty=fixed_rw_scsi:nc#3992:nt#19:ns#59:ss#1024:rm#5411:\
:fp#160:bp#0:ng#0:gs#0:ga#0:ao#0:\
:os=sdmach:z0#32:z1#96:hn=localhost:ro=a:\
:pa#0:sa#512000:ba#8192:fa#1024:ca#8:da#4096:ra#10:oa=time:\
:ia:ta=4.3BSD:\
:pb#512000:sb#512000:bb#8192:fb#1024:cb#8:db#4096:rb#10:ob=time:\
:ib:tb=4.3BSD:\
:pc#1024000:sc#716800:bc#8192:fc#1024:cc#8:dc#4096:rc#10:oc=time:\
:ic:tc=4.3BSD: \
:pd#1740800:sd#1536000:bd#8192:fd#1024:cd#8:dd#4096:rd#10:od=time:\
:id:td=4.3BSD: \
:pe#3276800:se#1150000:be#8192:fe#1024:ce#8:de#4096:re#10:oe=time:\
:ie:te=4.3BSD:
7.2 Formatting DEC DSP3105 with 1024-byte blocks.
DEC, DSP3105 DPS3105, 1024 block size disktab
A DEC DSP3160S was reformatted with 1024-byte blocks using the
following entry in /etc/disktab (two partitions)
# DEC DSP3160S
DSP3160S|DEC DSP3160S|DEC DSP3160S w/1024 b/sec as 2 partition:\
:ty=fixed_rw_scsi:nc#1302:nt#16:ns#75:ss#1024:rm#5403:\
:fp#160:bp#0:ng#0:gs#0:ga#0:ao#0:\
:os=sdmach:z0#32:z1#96:r0=a:\
:pa#0:sa#744000:ba#8192:fa#1024:ca#7:da#4096:ra#10:oa=time:\
:ia:ta=4.3BSD:\
:pb#744000:sb#818400:bb#8192:fb#1024:cb#7:db#4096:rb#10:ob=time:\
:ib:tb=4.3BSD:
7.3 My formatted disk has much less space then advertised!
filesystem, overhead disk space space, disk filesystem, space
Let's assume you bought a disk drive advertised with 400 MB
unformatted capacity. Vendors are not consistent with the MB
definition. You may have much less space less than you think you have.
Which of the following did you buy?
400 * 1000 * 1000 = 400,000,000 bytes
400 * 1024 * 1000 = 409,600,000 bytes
400 * 1024 * 1024 = 419,430,400 bytes
The disk must be formatted. This is often done by the vendor, but
occasionally by the user. Formatting maps the disk into sectors. Space
is reserved for the disk geometry and bad sectors. Formatting can take
10-20% of the capacity depending on the sector size. Common sector
sizes are 512 and 1024. Generally, bigger sectors mean less waste.
Once formatted, the UNIX file system must be created. On the NeXT,
this is one of the steps performed by the BuildDisk application. It
invokes the mkfs command to make a file system. This reserves space
for the UNIX file system (e.g., superblocks, inode tables). This
overhead can take another 2-3% of the available disk space.
If you issue the df command, you may be surprised to see another 10
the available disk space has disappeared. The df command shows the
total, used, and available disk space. The df units are in kbytes
(1024 bytes). The sum of the used and available numbers will generally
be about 10 allow the UNIX file system to be efficient in its storage
allocation. If your disk fills up, only the superuser can store files
in the remaining 10%.
To complete the picture, here's a snapshot of what may occur:
Capacity Lost/Used/Reserved Reason
(in bytes) (in bytes)
419,430,000 19,430,000 Marketing hype (~5\%)
400,000,000 60,000,000 Formatting (~15\%)
340,000,000 6,800,000 UNIX file system (~2\%)
333,200,000 33,320,000 Efficiency & superuser (~10\%)
299,880,000
For more information, refer to the df and mkfs man pages.
7.4 Initialing Opticals for NeXT
OD, NeXT optical disk, OD OD, initializing
Do the following:
/etc/mkfs /dev/rsd1a 288339 1803 2 8192 1024 12 10 60 4096 t
7.5 How to use a streamer ?
streamer
Using Configure.app add the SCSI streamer support driver in the
"Others" config.
7.6 How to recover from an partially formatted disk?
recover, disk
Often people (mostly on Intel) complain about a formatted disk
(sometimes partially) due to an installation process error of some
other OS. There is a chance to recover most of the data. The following
assumes you are on Intel, other hardware user have to handle things
much less complicated, but the way is similar:
* Prepare a new hard drive for booting
* Don't try to repair the broken drive!
* On Intel run fdisk to repartition the drive as it was before. If
you are not able to do this, you are lost. Delete all evtl. new
created partitions. By repartitioning, you won't loose data on the
drive.
* Run disk on the broken drive e.g. type disk -rsd1h.
* Now scan the disk for superblocks by entereing the scan command at
the interactive disk command prompt.
* If your disk was partially formatted, use a higher superblock
number to supply fsck with an new superblock. E.g. if a superblock
was found at 3145 use fsck -b3145 -y /dev/sd1a (assuming the first
partition is the broken one).
* After this run, it is most important to reboot without syncing the
drives! E.g. just turn off the computer without shutting down, or
use the reboot -n command.
* After rebooting the run fsck again, if it isn't done by the system
itself.
* You should be able to access the drive again now. Recovered files
are placed in the /lost+found directory.
_________________________________________________________________
* (weiter mit 8 Printing)
_________________________________________________________________
This document was converted from LaTeX using Karl Ewald's latex2html.