[Lustre-discuss] mdt backup tar --xattrs question

[Andreas Dilger]

On 2010-07-20, at 13:34, Ms. Megan Larko wrote:
> I hope this will be an easy one.   To conserve steps in backing up the
> metadata extended attributes of a Lustre mdt, I am looking at using a
> newer version of tar combined with its --xattrs option.   (Note:
> Previously I have used the mdt two-step back-up from the Lustre Manual
> and it has been successful.)   If I can backup the extended attributes
> via tar so that I don't have to issue both a getfattr and then a tar
> command it would be convenient.
> 
> I have GNU tar-1.23.  I was trying a version of the command indicated
> in http://lists.lustre.org/pipermail/lustre-discuss/2009-June/010794.html
> which supplied the --xattrs argument to the tar command.   It failed
> with "Unrecognized option --xattrs".     Is there something I need to
> specify to get tar to understand it is to back up extended attributes?
> 
> Will this version of tar correctly obtain the extended attributes or
> should I be using  lustre-tar  tool instead?

I don't think vanilla GNU tar 1.23 supports xattrs yet.  The RHEL5 patched tar (on which the Lustre-patched tar is based) DOES support xattrs.  You only need the Lustre-patched tar if you are expecting xattrs restored to a mounted lustre filesystem to preserve the striping.  Otherwise, regular RHEL5 tar should be enough for a backup/restore of the MDT xattrs mounted with "-t ldiskfs".

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