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Backup and restore replicas to tape using TSM RRS feed

  • Question

  • Hi

    I'm with a customer who has a IBM 3494 Library which is not recognized by DPM because the driver doesn't expose the library as media changer device.

    Because of that we want to create short term backups of our Hyper-V VMs to tape. We want to backup the DPM replicas to tape using the TSM agent.

    As far as I know the TSM Agent supports VSS.

    I found documentation how to backup the replicas but not on how to restore them (without rebuilding the whole dpm server)

    Can anyone give me a step by step guide?

     

    Thanks

    Alex

    Monday, November 7, 2011 3:14 PM

Answers

  • Hi,

    You should never restore 3rd party tape backup of DPM replica except for disaster recovery senario.  If you restore data from tape to a replica volume that was not missing and rebuilt, then two bad things can potentially happen.   1) The recovery point volume will most likely fill up since you are replacing all the files on the replica by overwriting them.  VSS is going to have to move all the original file data to the recovery point volume in order to maintain shadow copies.  2) If a consistency check is NOT ran after the restore from tape outside of DPM completes, then the next synchronization will change blocks on the older restored files that don't match the files on the protected server, and unrecoverable corruption will occur. 

     

    The only two DR senarios are:

    1) You lost the whole DPM server and the all of the disks in the storage pool.  In that case, you follow the documentation you have.

    2) One or more of the DPM storage pool disks failed. In that case, you have to:

    a. Manually delete all the failed NTFS volumes in Windows disk management (or using diskpart.exe) - then rescan the DPM storage pool disks. 
            DO NOT remove the missing disk(s) in the DPM storage pool. 
    b. You need to get the links to the various data source replica volumes that are missing by running this sql command from an administrative command prompt:

    osql -E -S localhost\MSDPM2010 -d DPMDB -Q "select ag.NetbiosName, ds.DataSourceName, vol.MountPointPath from tbl_IM_DataSource as ds join tbl_PRM_LogicalReplica as lr on ds.DataSourceId=lr.DataSourceId join tbl_AM_Server as ag on ds.ServerId=ag.ServerId join tbl_SPM_Volume as vol on lr.PhysicalReplicaId=vol.VolumeSetID and vol.Usage = 1 and and lr.Validity = 3 order by ag.NetbiosName"

    c. Replace the physical disk(s) and add the new disks into the DPM storage pool, then run dpmsync -reallocatereplica followed by DPMSYNC -SYNC to remake the missing volumes.
    d. Restore the replica volume data from tape backup for just the rebuilt replicas using the output of the SQL script as your restore guide. 
    e. Run a consistency check to get the volume back into a healthy state so scheduled backups can continue.

     


    Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    • Marked as answer by a.schmitt Tuesday, November 8, 2011 7:25 AM
    Tuesday, November 8, 2011 3:46 AM
    Moderator

All replies

  • Hi,

    You should never restore 3rd party tape backup of DPM replica except for disaster recovery senario.  If you restore data from tape to a replica volume that was not missing and rebuilt, then two bad things can potentially happen.   1) The recovery point volume will most likely fill up since you are replacing all the files on the replica by overwriting them.  VSS is going to have to move all the original file data to the recovery point volume in order to maintain shadow copies.  2) If a consistency check is NOT ran after the restore from tape outside of DPM completes, then the next synchronization will change blocks on the older restored files that don't match the files on the protected server, and unrecoverable corruption will occur. 

     

    The only two DR senarios are:

    1) You lost the whole DPM server and the all of the disks in the storage pool.  In that case, you follow the documentation you have.

    2) One or more of the DPM storage pool disks failed. In that case, you have to:

    a. Manually delete all the failed NTFS volumes in Windows disk management (or using diskpart.exe) - then rescan the DPM storage pool disks. 
            DO NOT remove the missing disk(s) in the DPM storage pool. 
    b. You need to get the links to the various data source replica volumes that are missing by running this sql command from an administrative command prompt:

    osql -E -S localhost\MSDPM2010 -d DPMDB -Q "select ag.NetbiosName, ds.DataSourceName, vol.MountPointPath from tbl_IM_DataSource as ds join tbl_PRM_LogicalReplica as lr on ds.DataSourceId=lr.DataSourceId join tbl_AM_Server as ag on ds.ServerId=ag.ServerId join tbl_SPM_Volume as vol on lr.PhysicalReplicaId=vol.VolumeSetID and vol.Usage = 1 and and lr.Validity = 3 order by ag.NetbiosName"

    c. Replace the physical disk(s) and add the new disks into the DPM storage pool, then run dpmsync -reallocatereplica followed by DPMSYNC -SYNC to remake the missing volumes.
    d. Restore the replica volume data from tape backup for just the rebuilt replicas using the output of the SQL script as your restore guide. 
    e. Run a consistency check to get the volume back into a healthy state so scheduled backups can continue.

     


    Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    • Marked as answer by a.schmitt Tuesday, November 8, 2011 7:25 AM
    Tuesday, November 8, 2011 3:46 AM
    Moderator
  • Thank you for your response. I came to the same conclusion sleeping a night over all this.  In my mind we have three scenarios:

    1. DR for the DPM Server
    2. Restore of a still existing VM from a tape backup
    3. Restore of a missing VM from a tape backup.

    The approaches are.

    1. Rebuild DPM Server, Restore DB, Restore Replicas from the latest available Backup as described in the DPM documentation
    2. Restore the VM from tape directly to the Hyper-V host (GUIDs are identical)
    3. Create a new VM restore the VHD from tape

    Regards

    Alex

     

    Tuesday, November 8, 2011 7:31 AM