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

Frederik Ferner frederik.ferner at diamond.ac.uk
Wed Sep 8 02:35:10 PDT 2010

Hi Bernd,

Frederik Ferner wrote:
> Bernd Schubert wrote:
>> On Thursday, September 02, 2010, Frederik Ferner wrote:
>>> we are currently reviewing our backup policy for our Lustre file system
>>> as backups of the MDT are taking longer and longer.
>> Yes, that is due to the size-on-mds feature, which was introduced into 
>>  See bug 
>> https://bugzilla.lustre.org/show_bug.cgi?id=21376
>> It has a patch, that also got accepted in upstream tar last week. You may find 
>> updated RHEL5 tar packages on my home page:
> Thanks, I'll give that a go.

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...).

> (Any chance of adding the SRPM to your download page?)

Thanks for the tar file.

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)?


Frederik Ferner
Computer Systems Administrator		phone: +44 1235 77 8624
Diamond Light Source Ltd.		mob:   +44 7917 08 5110
(Apologies in advance for the lines below. Some bits are a legal
requirement and I have no control over them.)

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