[Lustre-discuss] Could I restore OST without EA ?

[Dilger, Andreas]

On 2015/02/12, 2:47 AM, "Tung-Han Hsieh" <thhsieh at twcp1.phys.ntu.edu.tw>
wrote:

>We have a Lustre filesystem (version 1.8.8) in our lab, which
>contains several about 20 OSTs and only one MDT. Recently one
>of our file server got serious crashed. It contains 4 OSTs
>stored in RAID 5. We sent the file server to data rescue company.
>They told me that they can rescue all the data files, but the EA
>of these files may be lost.
>
>In the Lustre Operational Manual, I learn that to restore the
>MDT in filesystem level, we should restore both all the files
>as well as their EAs. But how about OST ? Could we restore it
>without the EA of files ? I mean, without running this ?
>
>	setfattr --restore=ea.bak
>
>If very fortunately I can restore it without EA, what is the
>next I should do to bring the whole filesystem to be in a
>consistant state ?

That depends on whether there is other corruption in the OST filesystems.
You do not need the OST EAs for normal usage, but if the OST directory
structure is corrupted then the EA data is useful to rebuild the OST
directory structure (use ll_recover_lost_found_objs to move objects from
lost+found/ into O/0/d*/ directories).

Cheers, Andreas
-- 
Andreas Dilger

Lustre Software Architect
Intel High Performance Data Division