[rescue] Low-level SCSI formatting.

Sheldon T. Hall shel at cmhcsys.com
Tue Dec 31 12:22:42 CST 2002

In response to my query about SCSI disk re-formatting, "Mike Meredith"
<mike at blackhairy.demon.co.uk> said ...

> There's sformat
> (http://freshmeat.net/redir/sformat/14755/url_tgz/sformat-3.5.tar.gz)

I didn't need it this time, but I'll file the ref for next time.

> I've never been keen on re-using disks that have started misbehaving.

This is a very non-critical application.

... and "Geoffrey S. Mendelson" <Geoffrey.Mendelson at mobileye.com> said ...

> You can't actually reformat a modern SCSI drive the way you would reformat
> an MFM type drive, i.e. rewriting all the servo and error correcting
> information, effectively zeroing out the drive and starting over.
> On the older < 1 gig 5 1/4" drives you do just that, and I had good
> luck with a long gone WD 7000 Fassst controler reformating the drive
> from 512 byte sectors to 1024 byte sectors and back again.
> On modern drives, you are really just doing an exhaustive read/write
> test and remaping bad blocks at the drive microcode level. For you
> this would be fine as it would put new blocks in the place of your
> defective ones.

So it seems to have been.

Thanks for the background, too.

... and Monty Walls (mwalls at castor.oktax.state.ok.us) wrote ...

> sformat is very nice. Will even allow you to alter sector size on drives
> have support that.  Very serious software that allowed me to take Tandem
> Raid Scsi drives and use them in my Sparc-20.

I'll remember that for next time!  Some of the bulk disk deals on eBay are
for disks with various odd formatting and firmware.

... In the event, I just used "fx -x" on the SGI.  It did a read-write test,
added the four bad sectors to the bad-block list, partitioned the drive, and
made it into a new "option disk."  It could hardly have been simpler.

The disk is used for staging ISOs for CD burning, and having this "new"
2-gig disk instead of the old 1-gig means I can have both the original
material _and_ the ISO on the one disk, making things a little simpler.

This is a pretty non-critical use, since no data stays there more than a day
or so; the data to be burned lives elsewhere, and I just move it to the
"new" disk for editing and re-arranging.  If the "new" disk craps out, I've
lost a little time, but no data.



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