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Hyper-V Backup question

    Question

  • - Wanted to backup a Hyper-V Host (Windows Server 2008 Core, x.64, with SP2) according KB http://support.microsoft.com/kb/958662/en-us
    - The file server data on a file server VM (Windows server 2008, x.64, with SP2) is on a dynamic disk within the VM. The reason for that is that it's possible that we have to extend the volume in the future, and that's only possible with dynamic disks.
    - Have now seen to my surprise that Windows Backup takes our VM offline during the Windows Backup operation! There is a little remark in http://support.microsoft.com/kb/958662/en-us that dynamic disks cannot be backed up online.

    My question: Does this change with Windows server 2008 R2? Will R2 be able to backup a hyper-v host without taking offline the Windows 2008 servers VM's that contain dynamic disks?

    Thank you all in advance for any help
    Franz 
    Thursday, August 27, 2009 9:57 AM

Answers

  • Hi,

     

    The downtime when Hyper-V perform a "save state" is really depends on the number of VMs and the applications running inside the VMs. If you don’t want to have a downtime, you may perform the follow suggetion:

     

    Understanding online and offline backups

     

    Whether a backup is performed online or offline depends on whether the backup can be performed without downtime.

    An online backup can be performed with no downtime on a running virtual machine when all of the following conditions are met:

    · Integration services are installed and the backup integration service has not been disabled.

    · All disks being used by the virtual machine are configured within the guest operating system as NTFS-formatted basic disks. Virtual machines that use dynamic disks or the FAT32 file system prevent an online backup from being performed.

    · Volume Shadow Copy Service must be enabled on all volumes used by the virtual machine with a specific configuration. Each volume must itself as the storage location for its shadow copies and that mapping must be available to the Hyper-V VSS writer. In other words, the shadow copy storage of C: should be on C:, the shadow copy storage of D: should be on D:, so on an so forth.

    If an online backup cannot be performed, then an offline backup is taken. This type of backup results in some degree of downtime. A variety of factors can affect the time required to take an offline backup. If the virtual machine is running or paused, it is put into a saved state as part of the offline backup process. After the backup is completed, the virtual machine is returned to its existing state.

     

    For more information, you can refer to:

     

    Backing Up Hyper-V Virtual Machines

    http://blogs.technet.com/virtualization/archive/2008/08/29/backing-up-hyper-v-virtual-machines.aspx

     

     

    Best Regards,

    Vincent Hu

     

    • Marked as answer by FranzSchenk Friday, August 28, 2009 11:07 AM
    Friday, August 28, 2009 8:27 AM

All replies

  • Hi,

     

    As far as I konw, you still can't backup a hyper-v host without taking offline the Windows 2008 servers VM's that contain dynamic disk in Windows Server 2008 R2 with Hyper-V enabled.

     

    Best Regards,

    Vincent Hu

     

    Thursday, August 27, 2009 12:03 PM
  • Hi,

    Thank you for your clarification.

    Have seen that when performing backups of the hyper-v host without shutting the VM down, windows backup automatically puts the VM (with a 500GByte fixed sized VHD on a dynamic disk) for about 10 minutes into the saved state.

    Is this type of backup supported (have a downtime of about 10 minutes), or do we have to take the VM completely offline during the backup (would be a downtime of about 6 hours, which will not be acceptable for our customer).

    Thank you in advance for any help!
    Franz
    Thursday, August 27, 2009 12:58 PM
  • Hello,

    I've had the same situation when I've configured VSS aware backups of running virtual machines that have internal dynamic disks.  I would suspect that "save state" backups would be supported, though certainly it would be better if the disks could be backed up "live" with no downtime.  I recently built a system where the VHDs are dumped to another server nightly using WSB.  Pretty awesome and inexpensive.  

    Nathan Lasnoski
    Friday, August 28, 2009 5:27 AM
  • Hi,

     

    The downtime when Hyper-V perform a "save state" is really depends on the number of VMs and the applications running inside the VMs. If you don’t want to have a downtime, you may perform the follow suggetion:

     

    Understanding online and offline backups

     

    Whether a backup is performed online or offline depends on whether the backup can be performed without downtime.

    An online backup can be performed with no downtime on a running virtual machine when all of the following conditions are met:

    · Integration services are installed and the backup integration service has not been disabled.

    · All disks being used by the virtual machine are configured within the guest operating system as NTFS-formatted basic disks. Virtual machines that use dynamic disks or the FAT32 file system prevent an online backup from being performed.

    · Volume Shadow Copy Service must be enabled on all volumes used by the virtual machine with a specific configuration. Each volume must itself as the storage location for its shadow copies and that mapping must be available to the Hyper-V VSS writer. In other words, the shadow copy storage of C: should be on C:, the shadow copy storage of D: should be on D:, so on an so forth.

    If an online backup cannot be performed, then an offline backup is taken. This type of backup results in some degree of downtime. A variety of factors can affect the time required to take an offline backup. If the virtual machine is running or paused, it is put into a saved state as part of the offline backup process. After the backup is completed, the virtual machine is returned to its existing state.

     

    For more information, you can refer to:

     

    Backing Up Hyper-V Virtual Machines

    http://blogs.technet.com/virtualization/archive/2008/08/29/backing-up-hyper-v-virtual-machines.aspx

     

     

    Best Regards,

    Vincent Hu

     

    • Marked as answer by FranzSchenk Friday, August 28, 2009 11:07 AM
    Friday, August 28, 2009 8:27 AM