I recently encountered JFS filesystem corruption on a system which
suffered memory corruption.  I was unaware of this failure until
fsck's of the filesystem in question failed and caused system
instability.  I ran memtest86+ and discovered that several bits of ram
had failed.  The error messages from the first fsck failure were
roughtly "duplicate filehandle", but I don't have logs so I can't
provide an exact report.

I removed the bad ram and began efforts to recover the system.  I then
booted the system using an Ubuntu Karmic live CD and tried to back up
the data via a simple cp -a <src> <dest>.  This failed upon reaching
one of the corrupted files, and additionally left the target (also
JFS) filesystem damaged.  I had to reformat the target filesystem and
try again.

I was able to use ls -Rl to discover which files had been lost.  But
it provided very cryptic error messages:

.....
ls: cannot access ./lib/firmware/2.6.28-3-rt/emi62: Stale NFS file handle
ls: cannot access ./lib/firmware/2.6.28-3-rt/korg: Stale NFS file handle
ls: cannot access ./lib/firmware/2.6.28-3-rt/sun: Stale NFS file handle
ls: cannot access
./lib/linux-restricted-modules/2.6.28-15-generic/wlan: Stale NFS file
handle
ls: cannot access
./lib/modules/2.6.27-14-generic/kernel/drivers/input/joystick/interact.ko:
Stale NFS file handle
ls: cannot access
./lib/modules/2.6.27-14-generic/kernel/drivers/input/joystick/joydump.ko:
Stale NFS file handle
ls: cannot access
./lib/modules/2.6.27-14-generic/kernel/drivers/input/joystick/magellan.ko:
Stale NFS file handle
ls: cannot access
./lib/modules/2.6.27-14-generic/kernel/drivers/input/joystick/sidewinder.ko:
Stale NFS file handle
.....

To my knowledge none of these files were ever mounted via NFS.

I used this list of failures as an exclusion list for rsync and was
then able to save almost everything from the ro-mounted filesystem.

I am waiting to reformat the partition because I wanted to file a bug
report to document the case.  Are there any recommendations as to what
data I should try to save from the disk and how I should find it?  I
want to complete this step quickly as I need to use the system for
work purposes.

Erik

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