[rescue] Low-level SCSI formatting.

[Geoffrey S. Mendelson]

Sheldon T. Hall wrote:
> The drive in question used to be the boot drive on the LX, but developed a
> bad sector where the Superblock wanted to live, and wouldn't fix itself.  I
> replaced it.  Opinions as to the efficacy of low-level formatting in this
> case solicited, as well.


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. 

The question is why are the blocks bad? If there is a bad spot on the
disk and it does not spread or contaminate the drive causing head
damage, you will probably be ok. For example, a marginal spot that
over the years deteriorated below useability. On the other hand
if something flaked off, it's likey to end up causing more and more
spots to fail.

If I were you, I would reformat it and give it to the person who keeps
complaining when you buy more backup tapes. :-)

Geoff.
-- 
Geoffrey S. Mendelson
MobilEye Vision Technologies Ltd, R.M.P.E House, 10 Hartom St. Har Hotzvim
Jerusalem, 91450 Israel Tel: +972-2-5417-356 Cell: +972-55-667-090
Do sysadmins count networked sheep?


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