[Lustre-discuss] recovering formatted OST

Andreas Dilger andreas.dilger at oracle.com
Wed Oct 20 00:46:31 PDT 2010


On 2010-10-19, at 17:01, Wojciech Turek wrote:
> Due to the locac disk failure in an OSS one of our /scratch OSTs was formatted by automatic installation script. This script created 5 small partitions and 6th partition consisting of the remaining space on that OST. Nothing else was written to that device since then. Is there a way to recover any data from that OST?

Your best bet is to make a full "dd" backup of the OST to a new device (for safety), first restore the original partition table.  If there was not originally a partition table, then you can just erase the new partitions:

  dd if=/dev/zero of=/dev/XXX bs=512 count=1

Then run e2fsck -fy, followed by "ll_recover_lost_found_objs" (from a newer lustre RPM, if you don't have it).  It is likely that you will get some or most of the data back.  This depends heavily on exactly what was written over the original filesystem. 

If it was just a new partition table, there should be relatively little damage (ext3 is very robust this way, and can repair itself so long as the starting alignment is correct).  If there were filesystems formatted in each of these partitions, then the amount of data available will be reduced significantly.

Cheers, Andreas
--
Andreas Dilger
Lustre Technical Lead
Oracle Corporation Canada Inc.




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