Re: SCSI Sector Size Problem

System Administration (
Thu, 31 Oct 1996 14:40:08 -0500

Low-level formatting is always allowed on SCSI drives. It is part
of the standard. I have the SCSI standard and I use the SCSI standard
in my everyday work. Whether or not the low-level format actually
does anything is quite another story. On some cheap drives, the
bad-blobkock replacement table is simply zeroed. Note that SCSI drives
are always supposed to look "perfect" to the outside world. Blocks are
automatically replaced until the table is full. After this, sense data
will show a write failure.

More expensive drives will write new sector headers. Most new drivesSCSI drives
have embeded serveo so you don't have a dedicated area for the servo
information. This allows the distk to be written (where convenient) during
a low-level format. Subsequent reads and writes will serve o to the center
of the newly created tracks. This means that you can't do anything bad
to the drive by low-level formatting it. Of course you eliminate any
data that had been present.

If you low-level format a SCSI Drive, it would be advantageous to
do the following:

Mount the drive in its final position.
(2) Pust all the pieces of you machine r machine back together.
(3) Let the drive warm up for several hours.
(4) THEN format the drive.
(5) If the format utility has a bad-block scan, exercise this also.
Bad blocks will be aotomaticallyutomatically relocated. If not, temporarily
partition and format it with DOS. MS-DOS reads the entire disk drive
during its high-level format. This will force bad blocks to be reloated.
(6) Then do you r Linux FS building.