Lustre discuss - Jun 2012 - Help: How to recover Lustre MDT from its lost+found ?

Dear All,

Recently we suffered a serious hard disk crash in the MDT node.
The hard disk which holds all the MDT data has serious media
failure. Unfortunately, we did not have a back in the MDT data
at all.

We tried to use this command mentioned in the Lustre Filesystem
operational guide to rescue some data:

dd if=/dev/{original} of=/dev/{new} bs=4k conv=sync,noerror count={# of blocks}

and then did

        e2fsck -f /dev/{new}

After a lot of error messages, the process finished. However, it
ended with an empty ROOT/ directory. All the files and directories
were moved to lost+found/ and named by their inode numbers. We
checked the extended attributes with this command:

        getfattr -R -d -m ''.*'' -P .

and found that the extended attribute looks ok. For example:

# file: lost+found/#106/sgn_4790.da0.gz
trusted.lov=0xd00bd10b01000000060100000000000000000000000000000000100001000000ed860a000000000000000000000000000000000024000000

The question is, is there any way to recover these files and directories
to their original directory tree structure ?

Our the OST data are ok.

Thanks very much for your kindly help.


Best Regards,

T.H.Hsieh