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Avoiding 2GB saveset chunks

Posted by Preston on 2009-08-19

Periodically a customer will report to me that a client is generating savesets in 2GB chunks. That is, they get savesets like the following:

  • C:\ – 2GB
  • <1>C:\ – 2GB
  • <2>C:\ – 2GB
  • <3>C:\ – 1538MB

Under much earlier versions of NetWorker, this was expected; these days, it really shouldn’t happen. (In fact, if it does happen, it should be considered a potential error condition.)

The release notes for 7.4.5 suggest that if you’re currently experiencing chunking in the 7.4.x series, going to 7.4.5 may very well resolve the issue. However, if that doesn’t do the trick for you, the other way of doing it is to switch from nsrauth to oldauth authentication on the backup server for the client exhibiting the problem.

To do this, you need to fire up nsradmin against the client process on the server and adjust the NSRLA record. Here’s an example server output/session, using a NetWorker backup server of ‘tara’ as our example:

[root@tara ~]# nsradmin -p 390113 -s tara
NetWorker administration program.
Use the "help" command for help, "visual" for full-screen mode.
nsradmin> show type:; name:; auth methods:
nsradmin> print type: NSRLA
                        type: NSRLA;
                        name: tara.pmdg.lab;
                auth methods: ",nsrauth/oldauth";

So, what we want to do is adjust the ‘auth methods’ for the client that is chunking data, and we want to switch it to using ‘oldauth’ instead. Assuming we have a client called ‘cyclops’ that is exhibiting this problem, and we want to only adjust cyclops, we would run the command:

nsradmin> update auth methods: "cyclops,oldauth",",nsrauth/oldauth"
                auth methods: "cyclops,oldauth", ",nsrauth/oldauth";
Update? y
updated resource id

Once this has been done, it’s necessary to stop and restart the NetWorker services on the backup server for the changes to take effect.

So the obvious follow up questions and their answers are:

  • Why would you need to change the security model from nsrauth to oldauth to fix this problem? It seems the case that in some instances the security/authentication model can lead to NetWorker having issues with some clients that forces a reversion to chunking. By switching to the oldauth method it prevents this behaviour.
  • Should you just change every client to using oldauth? No – oldauth is being retired over time, and nsrauth is more secure, so it’s best to only do this as a last resort. Indeed, if you can upgrade to 7.4.5 that may be the better solution.

[Edit – 2009-10-27]

If you’re on 7.5.1, then in order to avoid chunking you need to be at least on (that’s cumulative patch cluster 5 for 7.5.1.); if you’re one of those sites experiencing recovery problems from continuation/chunked savesets, you are going to need Alternatively, you’ll need LGTsc31925 for whatever platform/release of 7.5.1 that you’re running.


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