[Lustre-discuss] MDT backup (using tar) taking very long

[Andreas Dilger]

On 2010-09-08, at 3:35, Frederik Ferner <frederik.ferner at diamond.ac.uk> wrote:
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> I can now report that the backup was faster using this new version of 
> tar. It is still not really fast, though. the backup still takes nearly 
> 24h (that is running getfattr followed by tar...).

That surprises me a bit, unless you have a huge number of files. You should be able to do backups at least at the stat rate (5000/sec = 18M/hr is not unreasonable for almost any MDS). 

> I seem to remember that the separate getfattr call during the backup was 
> not required anymore with the new version of tar. A quick look in the 
> code seems to confirm this, at least it seems to be able to store the
> "trusted" extended attributes.
> 
> Can you confirm if 'tar --xattr --acl' on the ldiskfs mounted MDT is 
> sufficient to store all required extended attributes (and ACLs)?

Yes, that should work. It always is worthwhile to verify that they are restored correctly, however. You can just start a restore in some temp ext3 filesyste, interrupt it after some files in /ROOT have been restored, and use getfattr to verify the trusted.lov xattrs are restored. 

Cheers, Andreas