Restore from NDMP device mirror

I just came across an issue at customer site where Data Protector Device Mirror was used to duplicate NDMP backups. In general this is a great way to reduce the amount of time it takes to create separate sets of media at backup time. The worse thing is, this feature is not supported in Data Protector including version 7.01.

The backup will work as expected, but if you need to restore from the tape that was created using Mirror (not the original one) the session will just fail with the following error. Keep in mind, the restore from the original/primary media is working fine.

[Normal] From: RSM@decm01.syncer.de "" Time: 01.08.2012 13:56:35

Restore session 2012/08/01-50 started.

[Normal] From: RMA-NDMP@dema01.syncer.de "MSL8096_D2" Time: 01.08.2012 13:56:38

STARTING Media Agent "MSL8096_D4"

[Normal] From: RMA-NDMP@dema01.syncer.de "MSL8096_D2" Time: 01.08.2012 13:56:41

By: UMA@dema01.syncer.de@c32t0l0

Loading medium from slot 3 to device c32t0l0

[Major] From: RSM@decm01.syncer.de "" Time: 01.08.2012 13:57:27

Unknown internal error.

This looks pretty familiar, since there was the defect QCCR2A34355 that prevented NDMP restores from completing on 6.20 and 7.00.

DP 6.2 NDMP Restore with unknown error
http://support.openview.hp.com/selfsolve/document/KM1274902

Even with fixes/patches in place, the restore from Device Mirror (copy) will fail. This seems to be an issue with metadata not written correctly to DCBFs. omnidbcheck -sibf will show inconsistencies on all media used for device mirror.

I found a workaround for this issue that works pretty straight forward and allows you to restore the data.

  1. Identify the media(s) required for restore/restore chain using the restore dialog
  2. Load the tapes into library if not already present and perform barcode scan
  3. Check which session is stored on media(s)
  4. Remove data protection from session(s) in IDB that is used on that media to allow export (if not already expired)
  5. Export media(s) in question from IDB (right click on Slot -> Export)
  6. Import the media(s) in question back to IDB (right click on Slot -> Import) / make sure you select “Import Copy as Original” and “Log all”

Leave a Reply