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DPM 2010 with Hyper-V: Replicas versus Recovery Points RRS feed

  • Question

  • I'm trying to understand how replicas work.  We have DPM 2010 set to perform backups of the virtual machines on a Hyper-V host.  I've set it up to do a one-time replica in off-hours and then make a recovery point every day for a few days.

    My question is, does it ever automatically synchronize the replica?  I see there is an option to manually do it, but if I just leave it alone for months, will it do it on its own?

    For example: Say I select a retention period of 3 days.  It creates a replica the first day, then after that it starts creating recovery points.  On the 3rd day, does it just over-write the oldest recovery point?  Or does it ever start pushing them into the replica?  If it doesn't ever push them in, it would seem in a year or two I would have a very old replica, which isn't a good thing.

    So can anyone help me understand this better?

    Thanks in advance.

    Tuesday, May 3, 2011 1:35 PM

Answers

  • Hi

    When you create a protection group you will add primary workloads like Hyper-V hosts to your protection group. During the process of creating the protection group you will have three oprions of making the replica, now, scheduled or manually.

    When DPM creates the replica if copies the data (in this case the VHD files) from the Hyper-V hosts storage or CSV volume using local Hyper-V VSS. Using the VSS technuiqe DPM will only transfer block-level changes of the original data, during the replica creation the whole VHD will be copied. When the replica is created you will have all the VHD's copied to your replica volume in your DPM server.

    Now the fun part begins, depending on how often you choose to create a recovery point DPM will only transfer the block-level changes from the Hyper-V host to the DPM servers Recovery point volume. So if you choose to create a recovery point everyday at 11pm all the block-level changes from 11 pm the former day will be transfered and DPM will create a recovery point.

    Every night at midnight DPM will luanch a powershell script called pruneshadowcopiesdpm2010.ps1 that will update the replica with the erliest recovery point located in the recovery point volume of the DPM server, but this happends only if the retention time is expired. In you case the night between day 3 and 4.

    For more information look at this TechNet link: http://technet.microsoft.com/en-us/library/ff399286.aspx

     


    Best Regards

    Robert Hedblom

    MVP DPM


    Check out my DPM blog @ http://robertanddpm.blogspot.com

    Tuesday, May 3, 2011 1:51 PM
    Moderator

All replies

  • Hi

    When you create a protection group you will add primary workloads like Hyper-V hosts to your protection group. During the process of creating the protection group you will have three oprions of making the replica, now, scheduled or manually.

    When DPM creates the replica if copies the data (in this case the VHD files) from the Hyper-V hosts storage or CSV volume using local Hyper-V VSS. Using the VSS technuiqe DPM will only transfer block-level changes of the original data, during the replica creation the whole VHD will be copied. When the replica is created you will have all the VHD's copied to your replica volume in your DPM server.

    Now the fun part begins, depending on how often you choose to create a recovery point DPM will only transfer the block-level changes from the Hyper-V host to the DPM servers Recovery point volume. So if you choose to create a recovery point everyday at 11pm all the block-level changes from 11 pm the former day will be transfered and DPM will create a recovery point.

    Every night at midnight DPM will luanch a powershell script called pruneshadowcopiesdpm2010.ps1 that will update the replica with the erliest recovery point located in the recovery point volume of the DPM server, but this happends only if the retention time is expired. In you case the night between day 3 and 4.

    For more information look at this TechNet link: http://technet.microsoft.com/en-us/library/ff399286.aspx

     


    Best Regards

    Robert Hedblom

    MVP DPM


    Check out my DPM blog @ http://robertanddpm.blogspot.com

    Tuesday, May 3, 2011 1:51 PM
    Moderator
  • Hello Robert,

    Thanks for explanations.

    Correct me if i'm wrong, but you mean replica is like a snapshot and recovery point is the delta, right ?

    Replica is created on day 0.

    If retention time is expired, replica merge with the earliest recovery point (day 1) and delete it.

    Recovery points from day 2 and 3 are still presents.

    So if retention time is expired, did replica merges every day with the earliest recovery point ?

    Thanks in advance.

    Cheers,


    http://blog.simaju.fr - Partage de connaissances et retour d'expériences.
    Wednesday, August 24, 2011 1:20 PM