[Beowulf] (no subject)

John Bushnell bushnell at chem.ucsb.edu
Fri Feb 16 17:34:49 PST 2007


   I used to do similar kinds of backups on our smallish clusters,
but recently decided to do something slightly smarter, and have
been using rsnapshot to do backups since.  It uses rsync and hard
links to make snapshots of /home (or any filesystem you want)
without replicating every single byte each time, that is, it only
saves changes to the file system.  So after the first time you
run it, only a relatively small amount of backup traffic is
necessary to get a coherent snapshot of the whole thing.  I set
up a seperate cheap box with a couple large drives and three
gig-ethernet cards, and each one plugs into a switch for one of
our clusters.  Now /home directories for all three clusters are
all backed up nightly with very little network overhead and no
intervention.  It has been running without a hitch, and it is
easy to add less frequent backups for /usr/local or the like that
I'd hate to lose.  Definitely worth the effort in my case!  And
it is trivial to export the snapshot directories (read-only of
course) back to the clusters as needed for recovery purposes.

     - John

On Fri, 16 Feb 2007, Nathan Moore wrote:

> Hello all,
> I have a small beowulf cluster of Scientific Linux 4.4 machines with common 
> NIS logins and NFS shared home directories.  In the short term, I'd rather 
> not buy a tape drive for backups.  Instead, I've got a jury-rigged backup 
> scheme.  The node that serves the home directories via NFS runs a nightly tar 
> job (through cron),
> 		root at server> tar cf home_backup.tar ./home
> 	root at server> mv home_backup.tar /data/backups/
> where /data/backups is a folder that's shared (via NFS) across the cluster. 
> The actual backup then occurs when the other machines in the cluster (via 
> cron) copy home_backup.tar to a private (root-access-only) local directory.
> 	root at client> cp /mnt/server-data/backups/home_backup.tar 
> /private_data/
> where "/mnt/server-data/backups/" is where the server's "/data/backups/" is 
> mounted, and where /private_data/ is a folder on client's local disk.
> Here's the problem I'm seeing with this scheme.  users on my cluster have 
> quite a bit of stuff stored in their home directories, and home_backup.tar is 
> large (~4GB).  When I try the cp command on client, only 142MB of the 4.2GB 
> is copied over (this is repeatable - not a random error, and always about 
> 142MB).  The cp command doesn't fail, rather, it quits quietly.  Why would 
> only some of the file be copied over?  Is there a limit on the size of files 
> which can be transferred via NFS?  There's certainly sufficient space on disk 
> for the backups (both client's and server's disks are 300GB SATA drives, 
> formatted to ext3)
> I'm using the standard NFS that's available in SL43, config is basically 
> default.
> regards,
> Nathan Moore
> - - - - - - - - - - - - - - - - - - - - - - -
> Nathan Moore
> Physics, Pasteur 152
> Winona State University
> nmoore at winona.edu
> AIM:nmoorewsu
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