fs corruption recovery

[Allison Henderson <achender@linux.vnet.ibm.com>]

Hi all,

I've had some internal folks contact me for help with some customers 
that are having file system corruption woes.  It's been so long since 
I've done any work on ext3/4 code it's hard for me to advise.  So I told 
them I would run the situation by the folks on these mailing lists to 
see if I can generate some more ideas for them.

They have a 17 TB ext3 file system on rhel 6.5.  Upon reboot, the system 
was not able to come up and reported errors with the super block.  Right 
now, getting the machine to boot is not a critical as just recovering 
customer data.  They are able to boot a rescue disk to run fsck and they 
report that it ran for a short while and showed a lot of inode errors, 
but eventually it seg faulted.  They can re-run the tool, and they were 
able to progress further on repeated runs, but they do not seem to be 
able to get further than about 75%.  They do not have the fsck core at 
this point in time, but I'm guessing the tool is likely running out of 
memory for a file system that large, and they say they are using an old 
fsck (from 2010).  They report having run fsck successfully on large 
file systems in the past, but normally the machine has 24GB, and this 
one has only 16GB due to a bad dim.  The plan at the moment is for them 
to fix the bad dim and try the latest fsck.

So the questions they had that I am hoping to get help for is are there 
any other options they can try for data recovery?  I am hoping that the 
extra memory and the updated fsck might be able to complete, but I'm not 
sure what has changed in the tool since then.  I can assist them to 
collect more information/cores.  Any help is appreciated!  Thx!

Allison Henderson