[Lustre-discuss] Backing up the OSSs and MDSs

Brian J. Murrell Brian.Murrell at Sun.COM
Fri Oct 31 12:02:33 PDT 2008

On Fri, 2008-10-31 at 19:38 +0100, Tim Bell wrote:
> For the OSSs, from what I can see, this can be achieved on a per-volume 
> basis using LVM and snapshotting.


> However, I feel uncomfortable with 
> this approach and would prefer something where I can restore an 
> individual file from backup if lost.

Then you need to do filesystem backups, not device backups.  You do
filesystem backups from a lustre client rather than on individual server
nodes.  This is no different than how you would back up any other
filesystem.  I believe there is coverage in the manual about filesystem
level backups.  You need to pay attention to being able to backup EAs
used for striping and so on if you wish to restore files with their
striping attributes intact.

> Is there another way other than 
> find with mtime to find the list of modified files in the file system ?

Some tools, such as gnutar have a "find all files newer than" feature
built into them.

> For the MDSs, I cannot see how to back up an online MDS.  If I do a 
> split mirror without quiesce and backup the ext3 file system of the 
> split-off mirror, I get an inconsistent state of database.

Right.  The closest you can come is to synchronize as best you can
taking the LVM snapshot of the MDT and all of the OSTs and then backing
each of the snapshots up at your leisure.

> I've seen various references to Amanda based systems but I've not been 
> able to find the code that implements it so I could evaluate 
> implementing the same thing with our TSM system.

Indeed, there was an announcement here a while ago from zamanda about
supporting Lustre but I have not seen nor heard anything since.


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