Networker

Re: [Networker] Backing up ISCSI LUNS

2009-09-09 22:18:17
Subject: Re: [Networker] Backing up ISCSI LUNS
From: Francis Swasey <Frank.Swasey AT UVM DOT EDU>
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Date: Wed, 9 Sep 2009 22:14:07 -0400
On 9/9/09 7:11 PM, Preston de Guise wrote:
On 10/09/2009, at 09:01 , dfields wrote:

I just found out something interesting that I thought that everyone else would want to know. First, my environment: Backup server is Windows 2003 running Networker 7.4.4 with some hotfixes. The linux client is 7.4.4 also.

We've been having a problem lately with backups either taking an extremely long time to run, or with the backup server crashing for no apparent reason. Last night, I was watching the backups, and I think I finally figured out why.

We use an Equallogic SAN, and I've created several LUN's that I'm mapping to some of our Linux Redhat servers. On a couple of them, I've got a directory structure similar to the following:

/u00
/u00/work
/u00/staging

Where /u00, /u00/work, and /u00/staging are all ISCSI LUNs. The last two LUNs are just mounted over top of directories in /u00 (and they are obviously mounted after /u00 is mounted). This isn't too different than doing this with NFS mounts.

During backups, the client is backing up the server with a saveset of All, which works ok in that it backs up /u00, /u00/work, and /u00/staging as different save sets, which is what you would expect it to do. But what it's not doing is skipping the "work" and "staging" directories when it's backing up the /u00 save set. I think it's because the client doesn't know that the work and staging directories are ISCSI mounts. If these were NFS mount points, then they would be skipped as part of the backup of /u00.

I ran some reports after the backup finished, and the backup for /u00 was much larger than it should have been.

I'm going to open up a ticket with EMC once I do some more testing and I can give them more information.

Opening a case with EMC on this would be a waste of time because NetWorker is behaving as intended and as we'd expect.

iSCSI is effectively meant to be presented as local storage, in the same way that a SAN/FC presented LUN should appear as local storage.

As such, NetWorker is doing the right thing - it wants to back it up.

To work around it - e.g., if you want to backup the LUN via the RedHat host or in some other fashion, you need to setup directives to skip/ignore those filesystems.

I'm going to disagree with Preston. Either, NetWorker should backup /u00 and not see /u00/work and /u00/staging as separate savesets, or it should see them as separate savesets and not backup /u00/work and /u00/staging as part of /u00 as well as separately.

You should definitely open an issue with EMC -- one piece or the other is wrong.

--
Frank Swasey                    | http://www.uvm.edu/~fcs
Sr Systems Administrator        | Always remember: You are UNIQUE,
University of Vermont           |    just like everyone else.
  "I am not young enough to know everything." - Oscar Wilde (1854-1900)

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