DPM 2012 R2 - how to optimize disk space consumption? RRS feed

  • Question

  • DPM reserves too much space on HDDs in its pool, which it never consumes. Here is an example:

    Storage pool summary - DPM report

    As we can see, half of the assigned space is not used. While it's not a big problem in the short run (DPM works in a VM with dynamically expanding disk volumes), it still requires me to assign too high upper size limit for its volumes thus heavily oversubscribing the accessible physical storage. As DPM shares that physical storage with other VMs, there is a risk of the volume becoming overfilled with backup data and the VMs stopping.

    Is it possible to somehow decrease that "disk allocated" space? There are related settings in protection groups' properties, but DPM doesn't allow me to decrease them.

    Evgeniy Lotosh
    MCSE: Server infractructire, MCSE: Messaging

    Monday, April 13, 2015 5:58 AM

All replies

  • Hi,

    It seems that you need to re-architect your storage pool for DPM server. A backup is needed to protect the data on the storage pool. You could also migrate the data on the old disk to the new smaller disk.

    For more detailed information, you could refer to the thread below:

    DPM Storage Pool

    Disk Allocated

    Best Regards,


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    Wednesday, April 15, 2015 2:11 AM
  • This solution doesn't work. This incredible size of protection space is reserved during initial creation of protection groups. There is no obvious way to decrease it. The system simply doesn't allow to reserve less space.

    The system calculates the "needed" volume of space by using strange coefficients and formulas. I wonder if there is a way to change those coefficients.

    Evgeniy Lotosh
    MCSE: Server infractructire, MCSE: Messaging

    Wednesday, April 15, 2015 5:08 AM
  • Yes, by default DPM allocate extra space. However you can run below power shell script to give you clue which volumes can be shrunk which have enough space. This was for DPM 2010 but I have tested it successfully on DPM 2012 R2. This will show you shrinkable volumes and then you can manually shrink by modifying disk allocation.

    • Proposed as answer by V Jay Rana Thursday, April 16, 2015 6:47 PM
    • Unproposed as answer by Evgeniy Lotosh Friday, April 17, 2015 6:19 AM
    Thursday, April 16, 2015 6:47 PM
  • No, it's still not a solution I seek. You can shrink only recovery volumes in this way, and even they can be shrunk very little comparing to the total reserved volume of space. We have about 1.2 Tb of protected data, and DPM reserves twice as much space for replica volumes (2.9 Tb by now). For example, for protecting an SQL database 13 Gb in size, DPM reserves 150 Gb as a replica volume. Protecting a file server share 934 Gb in size requires reserving 1800 Gb. And so on. DPM forbids me to decrease replica volumes because it thinks it's the necessary minimum.

    The question is, how to tell DPM that it mandatorily reserves too much space for protection?

    Evgeniy Lotosh
    MCSE: Server infractructire, MCSE: Messaging

    Friday, April 17, 2015 6:32 AM
  • Did you ever manage to find a solution to this?

    I'm having the same issue though mine isn't quite as big a gap as yours (but still amount to nearly 7 GB of wasted space).

    Monday, June 27, 2016 1:03 PM
  • Any update on a solution?  Looking for an answer for the exact question you are posting.  Thanks .
    Wednesday, February 8, 2017 12:49 AM
  • Found this in a TechNet document on DPM.

    "If you discover that you have allocated too much space for the protection group, the only way to decrease allocations for a data source is to remove the data source from the protection group, delete the replica, and then add the data source back to the protection group with smaller allocations."

    Here is the link if you need more information.

    Hope this helps.

    Olumide Rotimi

    Monday, April 10, 2017 7:04 AM