Enterprise Software Thread, DPM 2012 overwrite not append in Technical; Hi all,
Any DPM gurus around?
I have a problem with our tape backup. We have 2 standalone LTO4 tapes ...
21st July 2012, 02:53 PM #1
DPM 2012 overwrite not append
Any DPM gurus around?
I have a problem with our tape backup. We have 2 standalone LTO4 tapes that do full backups from separate groups over night every night.
The problem we have is that when a tape comes back in the rotation, DPM appends the new backup and then errors because it has run out of space and no new tape is available(which is right, as it is standalone, and not a library)
Is there anyway for DPM to overwrite every time, rather than append?
Any help appreciated.
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23rd July 2012, 02:26 PM #2
- Rep Power
Originally Posted by CAWJames
I'm not sure what setup you have from your description. How do you backup to two tapes each night with only a standalone drive? Do you start one backup in the afternoon which completes before you leave, thus enabling you to swap the tape over in time for the night backup?
It sounds like the last backup on the tape has not expired (is still within the retention range) when the next backup is due to start. To protect the unexpired data it appends rather than overwrites. What version of DPM are you using? What retention range have you setup for these backups? When you insert the tape is it showing as expired? It has to be for DPM to overwrite it. Examine the backup sets on the tape, right click, to see when each backup source is due to expire. Is tape Co-location enabled?
The above article on Co-location tweaks may be useful.
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Last edited by Bruce123; 23rd July 2012 at 02:28 PM.
23rd July 2012, 03:11 PM #3
Sorry, we have 2 standalone drives! Should have mentioned that.
24th July 2012, 10:15 AM #4
Right, as we run a 3 week rotation, and I have retention set to 3 weeks, maybe the content isn't quite expiring in time for it to be overwritten.
I have changed the retention to 2 weeks and keeping the 3 week rotation, will see what happens.
Thanks for the input
24th July 2012, 05:47 PM #5
- Rep Power
There is a bug in DPM 2010 where recovery points don't quite expire in time causing the backup to fail when the tape is reused and I think it still exists in 2012. I thought it just applied to libraries though. Microsoft said that they were working on a fix back in January, but I haven't heard anything yet.
Your solution should work, but the problem is that the tape catalogues will automatically get pruned (deleted) when the recovery points expire (one week early in your case). In 2010 there was nothing that I could do about it. But I have the impression that in 2012 it allows you to adjust how long they are retained beyond the date the recovery points are due to expire. I've not tried 2012, so I can't say for sure, but if you can you could set DPM to retain the catalogue for an extra week.
Or.... If you can specify the retention period in days rather than weeks, you could you set it to 20 days rather than 3 weeks, giving the recovery points one full day to expire.
If the tape catalogues are pruned you can still recover from the tape, but only as a single flat file / set of files for each recovery point. E.g. If you are protecting all files on a drive on a server, you have to recover the entire backup to a network share (possibly as a VHD file, then mount it to find the individual file/folder). Not a position you want to find yourself in.
The MS DPM team still has a lot of work to do to improve the way it deals with tapes and tape libraries.
Hope this helps.
Sent from Android.
Last edited by Bruce123; 24th July 2012 at 06:24 PM.
Thanks to Bruce123 from:
CAWJames (24th July 2012)
24th July 2012, 10:13 PM #6
Good old MS, their age old trick of using the general public as beta testers!
The days instead of weeks looks like a good one, might try that, if after the next 3 weeks we get the same problem, or the catalogue problem you describe.
I am going to regret saying this, but I've never had to restore from tape, I've just dipped into the disk backups, either onsite or offsite, and restored from there. The tapes are mainly as a total disaster backup.
You watch, tomorrow all hell will break loose after saying I've never had to restore from tape!!
Thanks for the replies, hopefully MS will issue some DPM updates in the next month or so.
6th August 2012, 07:25 PM #7
- Rep Power
Just to let you know that MS have released update rollup 4.0.1915.0 which includes a fix for this issue:
Tapes are marked as reusable on the next day after the date of expiry as DPM runs a reclamation job only at midnight. If you want the tape to be reusable on the same date as it is expired, create the ExpireDatasetOnDayStart 32- bit DWORD, and set its value to 1 under the following registry key:
HKEY_LOCAL_MACHINE\Software\Microsoft\Microsoft Data Protection Manager\Configuration\MediaManager
See Description of Update Rollup 2 for System Center 2012 for more info.
Looking at the release date it was released hours from when you posted your response. Perhaps MS perused these forums and decided to release it earlier than planned!
Mind you it's a pretty stupid bug if you ask me, and I'm amazed that it has taken this long for a fix. The fix is also included in the rollup for 2010.
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