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VSS snapshots for DPM 2010 Hyper-V backup conflict with SQL backup on a virtual SQL server

    Question

  • We currently use DPM 2010 to backup our virtual servers which reside on a 5 node Hyper-V clustered share volume.  DPM uses the hardware VSS writer to backup the Hyper-V guests.   Several of these Hyper-V guests are SQL servers (SQL 2008) and they are all configured to run point in time SQL backups using SQL Management Plans.

    The SQL backups are scheduled to run a full database backup on a Friday and differential backups on the other days of the week.  Transaction backups are scheduled to run several times throughout the day.

    However we have recently discovered that there is a conflict between these two methods as it seems as though when a restore is required using a differential SQL backup, it fails as the snapshot created by DPM forces SQL to believe it has had a full backup carried out externally from the Management Plan and is therefore unable to perform the restore.

    DPM backs up the Hyper-V guests on a daily basis from 8pm.

    Can anyone provide any advice or guidance on this as we need both types of backup to run successfully.  We are required to backup SQL with point in time backups and we also need to protect the Hyper-V guests in their entirety.

    Monday, May 21, 2012 4:29 PM

Answers

  • Hi,

    As per the following article, the solution it to set this registry key inside the Virtual machine. running the SQL server.

    975354  A Hyper-V update rollup is available for Windows Server 2008 R2
    http://support.microsoft.com/default.aspx?scid=kb;EN-US;975354

     

    Issue 3

    The application backup operation in the virtual machine (VM) is incorrectly affected by the VM backup operation on the server that is running Hyper-V.

    Location: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Virtualization\VssRequestor
    Name: BackupType
    Type: REG_DWORD
    Value: 0 or 1

    If this registry entry is created and its value is set to 1 , application backup will not be affected by the virtual machine backup operation on the server that is running Hyper-V. If this registry entry does not exist, or if its value is 0 , issue 3 occurs.


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.

    Monday, May 21, 2012 6:51 PM
    Moderator

All replies

  • Hi,

    As per the following article, the solution it to set this registry key inside the Virtual machine. running the SQL server.

    975354  A Hyper-V update rollup is available for Windows Server 2008 R2
    http://support.microsoft.com/default.aspx?scid=kb;EN-US;975354

     

    Issue 3

    The application backup operation in the virtual machine (VM) is incorrectly affected by the VM backup operation on the server that is running Hyper-V.

    Location: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Virtualization\VssRequestor
    Name: BackupType
    Type: REG_DWORD
    Value: 0 or 1

    If this registry entry is created and its value is set to 1 , application backup will not be affected by the virtual machine backup operation on the server that is running Hyper-V. If this registry entry does not exist, or if its value is 0 , issue 3 occurs.


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.

    Monday, May 21, 2012 6:51 PM
    Moderator
  • Thanks Mike

    I will look into this and update the post with our results.

    We also have two more scenarios which are apparently affected by this:

    1. A Windows 2003 Enterprise server (Hyper-V client) with SQL 2008 installed - it is also experiencing the same issue on all it's databases.

    2. A Windows 2003 R2 x64 (physical) server with SQL 2008 installed - this appears to be experiencing the issue, but only on the system databases.

    Are there any known issues for these (i.e Windows 2003 OS on a Hyper-V client, and Windows 2003 physical server (affects system databases only)?

    Tuesday, May 22, 2012 10:16 AM
  • HI,

    For 1) - The solution is the same, add the registry key to the virtual machine.

    For 2) - Only databases using FULL recovery model will have the  SQL logs truncated by SQL during incremental backup.  If you don't want SQL to truncate the logs, then you need to adjust DPM and select the option to Synchronize "Just before a recovery point"  - that tells DPM that we don't want to peform incremental backups and only express full.  SQL will not truncate logs for FULL backups.


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.

    Tuesday, May 22, 2012 2:38 PM
    Moderator