NDMP policy file list being processed in wrong order
We have just upgraded out NetBackup v6.0MP6 environment to V6.5.3. It actually went remarkably smoothly compared to previous experiences, major or minor upgrade.
One of the issues we have logged with Symantec was the change in processing order of file lists in our NDMP backup policies.
In v6.0MP6, our multi-terabyte NDMP policy file list was specifically ordered to ensure the largest volume was processed first; it being over 1TB in size. The policy was set to allow multiple data streams and restricted to running only 2 at any one time. As the first large volume was processed, so do the smaller ones in turn whilst the first is continueing to run.
After our upgrade to v6.5.3 we have found, and reproduced in our test environment that the first 2 streams in the list get scheduled LAST; i.e. it's as if the processing of the file lists get reordered to move the first two file lists to the end, and then backups get scheduled in that order, not the order we had specified.
e.g. a file list of:
/vol/1/.snapshot/datastore_1
/vol/1/.snapshot/datastore_2
/vol/1/.snapshot/datastore_3
/vol/1/.snapshot/datastore_4
/vol/1/.snapshot/datastore_5
/vol/1/.snapshot/datastore_6
/vol/1/.snapshot/datastore_7
will actually get scheduled in the order:
/vol/1/.snapshot/datastore_3
/vol/1/.snapshot/datastore_4
/vol/1/.snapshot/datastore_5
/vol/1/.snapshot/datastore_6
/vol/1/.snapshot/datastore_7
/vol/1/.snapshot/datastore_1
/vol/1/.snapshot/datastore_2
This caused us some issues due to length of the whole backup stream.
A workaround appears to be to reorder the streams as follows:
/vol/1/.snapshot/datastore_6
/vol/1/.snapshot/datastore_7
/vol/1/.snapshot/datastore_1
/vol/1/.snapshot/datastore_2
/vol/1/.snapshot/datastore_3
/vol/1/.snapshot/datastore_4
/vol/1/.snapshot/datastore_5
This seems to ensure that stream /vol/1/.snapshot/datastore_1 starts first.
Anyone seen anything like this? As I mentioned above, a call is open with Symantec and they are investigating.
Malcolm
Comments
Hmmm ! I think NetBackup 6.5 wont follow the Backup as per mentioned Streams in Policy !
As an alternative you can create a new policy with largest stream backup selections for making that do run in first priority !
Thanks, Karthikeyan Sundaram.
Thought about a new policy; but I want to restrict my NDMP backups to 2 running streams only (leaving other drives free for other non-NDMP backups). Creating another policy locks another drive down to NDMP. Yes, I could create a specific Storage-Unit to handle this by restricting the number of concurrent drives and that's another workaround to what we've already discovered.
My main point here is that something has changed; NDMP file list processing alway used to follow the order and why wouldn't it? In my mind it should.
Malcolm
NBU v7.1.0.1 Master and Media servers on RHEL 5 & Win2008; SAN based LTO 3 and 4 tape libraries.
Linux, Solaris, Windows and OpenVMS clients.
PureDisk, SLP, VMware, Oracle, SQL/Server and Exchange agents
VBR and OpsCenter
I'd recommend getting a support case opened with Symantec on this one. If you do, please do share the results back in the post so they're available for all for reference for those that may also run into this.
Symantec say it's working as designed!
To follow up on this; Symmantec have spent a few weeks looking at logs and have finally determined that "NetBackup has worked as designed".
....
"If you created the backup policy at the first the backup will run 1, 2, 3, 4, 5, 6, 7.
NBU v7.1.0.1 Master and Media servers on RHEL 5 & Win2008; SAN based LTO 3 and 4 tape libraries.
Linux, Solaris, Windows and OpenVMS clients.
PureDisk, SLP, VMware, Oracle, SQL/Server and Exchange agents
VBR and OpsCenter
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