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Can DPM 2012 backup from multiple LUNs? RRS feed

  • Question

  • The scenario:

    • A cluster shared volume (CSV) with 2 LUNs in it. VMs (Managed with Hyper-V) with OS VHDs in one LUN and data VHDs in the other LUN.
    • DPM 2012 instaled in another server.

    With this configuration backup fails with message "The replica of Microsoft Hyper-V \Backup Using Child Partition Snapshot\<VMToBackup> on <VMToBackup> is inconsistent with the protected data source". Now, when we change data VHD from its LUN to the OS LUN, so all the VHDs and the VM is in the same LUN, the backup runs perfectly.

    So my question is, Is DPM 2012 able to backup VMs with its VHDs in multiple LUNs?

    Thanks a lot for your help!

    Wednesday, October 10, 2012 8:28 PM

Answers

  • Actually the vss software provider is not necessarily limited to serialized backups. Its the MS recommendation in http://technet.microsoft.com/en-us/library/ff634192.aspx but it can be adjusted by modifying the 'MaxAllowedParallelBackups' reg key on the DPM server. we currently have it set to 3 parallel backups at a time backing up VMs that have the data disk on one CSV and the OS disk on a different and we haven't received the error message you post.

    also, how many VMs are you trying to include on the DPM protection group? do you get the same error if you create a new protection group that includes only one VM that has your settings?

    • Proposed as answer by Ariel Delgado Friday, November 23, 2012 3:05 PM
    • Marked as answer by Leandro Cofre Thursday, December 13, 2012 12:25 PM
    Tuesday, November 13, 2012 8:29 PM

All replies

  • Hi Leanardo

    Do you mean a machine that have a vhd(x) on ClusterStorage\Volume1 and  ClusterStorage\Volume2 at the same time ?

    I just tested it with the same result as you , i will try to look for a official statement as most the of hyper-v documentation suggest splitting the os/data on mutiple csv's

    But a guess would be that the VSS writer cant/wont sync mutiple volumes at the same time.


    my blog is at http://flemmingriis.com , let me know if you found the post or blog helpfull or leaves room for improvement

    Wednesday, October 10, 2012 10:06 PM
    Moderator
  • Hi Flemming,

    Thank you very much for your answer. Is exactly what you understood: A backup for a machine with 2 VHDs, one in Volume1 and the other in Volume2, is meant to fail.

    Like you, I couldn't find a statement in Microsoft online documentation about DPM 2012 being unable to backup this kind of machines, and splitting in volumes is considered a best practice (here for example, http://technet.microsoft.com/en-us/library/ff182320).

    A statement from Microsoft clarifying this matter would be ideal.

    Thanks again for your kind assistance.

    Thursday, October 11, 2012 6:57 PM
  • Oh wow... thanks... I was looking (accidently) at this topic post.

    I was planning to upgrade a CSV storage with more space to split up disks for the guest as System, data and so on... to different Volumes ... now I should wait a bit. ;)

    Monday, October 15, 2012 5:03 PM
  • traied Again without failure , need to try to reproduce a few more times, but i think i would avoid if possible , to avoid shapshots across mutiple volumes.


    my blog is at http://flemmingriis.com , let me know if you found the post or blog helpfull or leaves room for improvement

    Monday, October 15, 2012 6:59 PM
    Moderator
  • I'm glad it was useful. :)

    Tuesday, October 16, 2012 12:00 PM
  • [...] avoid shapshots across mutiple volumes.

    In the meantime, it seems to be the best workaround.

    It's strange that Microsoft takes no position on the matter. Is this considered a wrong behavior to be corrected soon, or we should make this workaround the final solution?

    Thanks for your tests and answers!

    Tuesday, October 16, 2012 12:51 PM
  • backing up machines stored with all vhds together on one volume seems to be a better idea. 
    I couldn't get troubles with 3 volumes and several machines.
    Thursday, October 18, 2012 7:05 PM
  • Hi Leandro,

    Do you use serialization or San Hardware piloted Snapshots ?

    Ced

    Friday, October 19, 2012 2:54 PM
  • Do you use serialization or San Hardware piloted Snapshots ?

    Hi Ced,

    We use Hardware VSS provider, but we tested with Software VSS provider too with same results.

    Friday, October 19, 2012 5:36 PM
  • Hi Leandro,

    What hardware are you using for storage?

    I would say that SCDPM 2012 does in fact support backing up VMs that have the configuration you propose (data disks in two different CSvs) while maintaining the VM online. We've been doing it that way for a while using the windows vss provider with no issues.

    Franc

    Friday, November 9, 2012 10:37 PM
  • What hardware are you using for storage?

    I would say that SCDPM 2012 does in fact support backing up VMs that have the configuration you propose (data disks in two different CSvs) while maintaining the VM online. We've been doing it that way for a while using the windows vss provider with no issues.

    AAThomp,

    Thanks for your feedback.

    We are using a Dell MD3200. Unfortunately the windows VSS provider is not an option in our case. We need to take advantage of the parallel backup that gives the Hardware VSS provider. Software provider only allows serialized backups.

    Thanks for your interest in this matter.

    Tuesday, November 13, 2012 5:04 PM
  • Actually the vss software provider is not necessarily limited to serialized backups. Its the MS recommendation in http://technet.microsoft.com/en-us/library/ff634192.aspx but it can be adjusted by modifying the 'MaxAllowedParallelBackups' reg key on the DPM server. we currently have it set to 3 parallel backups at a time backing up VMs that have the data disk on one CSV and the OS disk on a different and we haven't received the error message you post.

    also, how many VMs are you trying to include on the DPM protection group? do you get the same error if you create a new protection group that includes only one VM that has your settings?

    • Proposed as answer by Ariel Delgado Friday, November 23, 2012 3:05 PM
    • Marked as answer by Leandro Cofre Thursday, December 13, 2012 12:25 PM
    Tuesday, November 13, 2012 8:29 PM
  • Thanks for your clarification. As you said, you can set the allowed parallel backups in the registry. However, I am not sure if you can backup many VMs at the same time if you have the next registry key: HKLM\Software\Microsoft\Microsoft Data Protection Manager\Agent\UseSystemSoftwareProvider

    Can you confirm that you are using Software provider and you are doing parallel backups concurrently? How many backups at the same time?

    Also, we have about 20 VMs in the DPM protection group that fails to backup. We have created test groups with 5 VMs and 1 VM. In all cases the backups fail. If all the VHDs are in the same CSV then the VM is successful backed up. If the VM can't be backed up and we can move all its VHDs to the same CSV and backup.


    Friday, November 23, 2012 6:30 PM
  • Yes: the Microsoft vss provider allows parallel backups (at least I haven't found anything suggesting otherwise). MS says 1 per time but you can change the registry in the DPM server. I've done it and seen it work successfully.

    Remember that the "UseSystemSoftwareProvider" key must be created on the Protected Server and the 'MaxAllowedParallelBackups' must be set in the DPM server. The 'MaxAllowedParallelBackups' is what tells the DPM server how many VMs to backup simultaneously (you must also delete the DataSourceGroups.xml file as per the footnotes of http://technet.microsoft.com/en-us/library/ff634220.aspx if you are planning to use a hardware vss) I couldn't find official documentation from MS on how to confirm that the backups were happening concurrently but here is what I did: first, measured the time it took when using parallel vs serial backups. second: on the DPM console, on the monitoring tab during the backup operation, I reviewed the size of the "Data transferred" column for each VM as the backup goes along. When serialized is enabled, this column value only increases for one VM at a time. when parallel is enabled, this column increases for multiple VMs at a time. all times using the MS vss provider. we keep a max of 3 VMs per time but we've done it with more and seen no problems. I would keep that value close to 1 though. I don't think 20 is a good idea. specially considering that you have your VM scattered across multiple CSVs.

    • Proposed as answer by Ariel Delgado Friday, December 7, 2012 8:44 PM
    Wednesday, November 28, 2012 10:40 PM
  • AAThomp,

    Thanks for the information you gave us.

    We can confirm DPM 2012 can backup VMs with disks in different volumes. After many twists and turns we decided to reinstall the hosts from the cluster. Then we upgraded the storage specific drivers, recently published ("Dell PowerVault MD Series Storage Array Resource DVD version 4.1.0.88" from here). After that, the error does not recurred.

    Thanks FlemmingRiis and Enrico Stephan too.

    Thursday, December 13, 2012 12:21 PM