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How DPM 2012 storage pool is used RRS feed

  • Question

  • Hello,

    When I create new protection group, DPM creates two logical volumes:

    • 1st for replica
    • 2nd for recovery points

    Schedule:

    sync every 1 hour;

    exspress full every 24 hours

    retention period 5 days.

     

    When DPM creates the initial replica and stores it on 1st volume; after one hour DPM syncs data changes and stores it to 2nd volume? How this scenario works with DPM? > I can't find information regarding this question, need help : )

    Thanks for your answers!

    Wednesday, December 19, 2012 9:01 AM

Answers

  • Hi,

    DPM simply relies on VSS snapshots for recovery points.  All DPM writes are performed on the replica volume, and VSS performs copy-on-write (COW) operations to save off the changed blocks to the recovery point volume.  This occurs anytime a synchronization or express full backup is taken.  The recovery point volume only contains changed blocks, not complete files. A recovery point job just makes a snapshot of the replica volume and then the process continues.  During a recovery, DPM mounts the VSS snapshot associated with the recovery point time you are restoring, and copies the older files back to the destination you specified during recovery. 


    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.

    Wednesday, December 19, 2012 8:21 PM
    Moderator
  • Hi,

    Q1) Is it true, what replica is updated firstly with the changed data and when RP are created and placed on RP volume?
    A1) No, that is not the way it works, block level changes applied to the replica volume during a Sync will result in VSS moving the old blocks to the recovery point volume in real time.

    For protected volumes or shares, including systemstate and client protection, the time of the recovery point is the time you will see under the recovery tab.  Synchronizations for file data are not recovery points.  However, with that said, if you needed to recover a file between the last recovery point, and before the next recovery pointy is created, you can manually create a recovery point and recover files from that intermediate recovery point assuming one or more synchronizations were successful in between.   

    So, if you are doing synchs every 15 minutes, and the last RP was at 12:00 noon, and at 3:25pm the protected server power supply goes belly up, the last synch was at 3:15pm, so you could manually make a recovery point without synchronization, and that restore point would include file changes up to and including 3:15PM, so in escence you only lost 10 minutes worth of changes before the server became inaccessible.  The longer time between synchronizations, the more changes you miss bringing over to the DPM server and potentially lose should the protected server croak.

    For file file protection Windows support 64 snapshots per volume, so based on your retention period, you could take more recovery points per day and have more recovery point times to choose from each day.   IE: 1 RP / day = 64 days max protection.   6 RP / day = ~ 10.5 days max protection.


    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.

    • Marked as answer by Rokaas Friday, December 21, 2012 8:10 AM
    Thursday, December 20, 2012 4:17 PM
    Moderator

All replies

  • Hi,

    DPM simply relies on VSS snapshots for recovery points.  All DPM writes are performed on the replica volume, and VSS performs copy-on-write (COW) operations to save off the changed blocks to the recovery point volume.  This occurs anytime a synchronization or express full backup is taken.  The recovery point volume only contains changed blocks, not complete files. A recovery point job just makes a snapshot of the replica volume and then the process continues.  During a recovery, DPM mounts the VSS snapshot associated with the recovery point time you are restoring, and copies the older files back to the destination you specified during recovery. 


    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.

    Wednesday, December 19, 2012 8:21 PM
    Moderator
  • Is it true, what replica is updated firstly with the changed data and when RP are created and placed on RP volume?

    DPM syncs data changes and writes it to replica (replica are always up-to-date in this case) and when RP are created (if it's set; I can only sync data without RP creation..).  

    In that case, if I want to get the most up-to-date data it's enough for me to have the data what resides on replica volume; but if I want to go back in time - I need data from RP volume? 
    • Edited by Rokaas Thursday, December 20, 2012 7:00 AM expanded
    Thursday, December 20, 2012 6:58 AM
  • Hi,

    Q1) Is it true, what replica is updated firstly with the changed data and when RP are created and placed on RP volume?
    A1) No, that is not the way it works, block level changes applied to the replica volume during a Sync will result in VSS moving the old blocks to the recovery point volume in real time.

    For protected volumes or shares, including systemstate and client protection, the time of the recovery point is the time you will see under the recovery tab.  Synchronizations for file data are not recovery points.  However, with that said, if you needed to recover a file between the last recovery point, and before the next recovery pointy is created, you can manually create a recovery point and recover files from that intermediate recovery point assuming one or more synchronizations were successful in between.   

    So, if you are doing synchs every 15 minutes, and the last RP was at 12:00 noon, and at 3:25pm the protected server power supply goes belly up, the last synch was at 3:15pm, so you could manually make a recovery point without synchronization, and that restore point would include file changes up to and including 3:15PM, so in escence you only lost 10 minutes worth of changes before the server became inaccessible.  The longer time between synchronizations, the more changes you miss bringing over to the DPM server and potentially lose should the protected server croak.

    For file file protection Windows support 64 snapshots per volume, so based on your retention period, you could take more recovery points per day and have more recovery point times to choose from each day.   IE: 1 RP / day = 64 days max protection.   6 RP / day = ~ 10.5 days max protection.


    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.

    • Marked as answer by Rokaas Friday, December 21, 2012 8:10 AM
    Thursday, December 20, 2012 4:17 PM
    Moderator