Recovering select files from a failing hard disk

[Chuck Swiger]

On Jan 12, 2007, at 1:18 PM, Garrett Cooper wrote:
> 1. Can I bypass mounting or reading certain sections of the  
> filesystem?

Sure, if you boot off some other device or a CD-ROM.

> 2. Can I force part of a drive to be remapped to other sectors?

Yes, but it is likely that modern drives will have automatically  
reassigned failing sectors already, until it ran out of spare  
sectors.  If you've got an older SCSI system, you might try running  
your adaptor's BIOS utility and having it do a device verify; that  
will encourage the drive to remap problematic sectors.

> 3. Is there a backup superblock on the disk and what would it be? I  
> know
> this feature exists on some filesystems, but I'm not sure if UFS is  
> one
> of those filesystems.

There are many backup superblocks kept on the disk; "fsck -b 32" will  
try using the first alternate, but there will be others scattered  
about.  You can run "dumpfs" to locate more, I believe.

> 	The reason for these questions is that I believe that the
> portion of my failing hard disk is involved with the statistics  
> portion
> for the data slice or a series of directories. So, I want to grab the
> files off my disk and just dump the thing asap.

OK.  You might try doing a block-copy with dd to a new drive, and  
then trying to fsck or repair the data on that copy rather than  
trying to fix the filesystem on the failing drive...

-- 
-Chuck