[svlug] scsi troubleshooting

Seth David Schoen schoen at loyalty.org
Mon Dec 3 00:21:02 PST 2001

J C Lawrence writes:

> If you have neither, then you're in for a job of some hours if not
> small order days (depending on how bad it is) working thru the disk
> with a sector editor piecing the bits back together (actually most
> of your time will be spend finding the bits to piece together).  

There are also some good tools to guess the boundaries of partition
tables; I've heard people say that some of them even tend to guess
correctly. :-)

I don't remember which one is the best; gpart is the only one I
remember, but I think there's another which may be more sophisticated.

Another priority might be determining whether the disk has suffered
some kind of physical failure, making parts of it unreadable or
scrambled, or whether it's just that particular data (like the
partition table) has been corrupted.

One approach to this is to do

dd if=/dev/sda of=/dev/null

and watch for physical hardware errors.  (This could take a while.)

Another is to do

strings /dev/sda | less

and look for actual readable useful information.

Seth David Schoen <schoen at loyalty.org> | Its really terrible when FBI arrested
Temp.  http://www.loyalty.org/~schoen/ | hacker, who visited USA with peacefull
down:  http://www.loyalty.org/   (CAF) | mission -- to share his knowledge with
     http://www.freesklyarov.org/      | american nation.  (Ilya V. Vasilyev)

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