How much space of an Hyper-V VM stor DPM? RRS feed

  • Question

  • Hi,

    How much space of an Hyper-V VM stor DPM, if there is emty space?

    How does DPM handel the VM disk vs files on the disk? 

    Or how do DPM handel the emty space on an VM disk, I think the data get compressed?


    Tuesday, March 21, 2017 10:16 AM

All replies

  • Hi,

    During initial replica creation (IR) for a VM DPM will basically copy the entire allocated range of the .vhdx file(s) to the DPM replica volume.  The resulting file(s) will be identical to the original .vhdx file(s).  During subsequent backups, DPM will only transfer blocks that were changed since the last backup and apply them to the replica.  In the case of DPM 2012 R2 and earlier, VSS snapshots are used for recovery points.  In the case of DPM 2016 using modern backup storage, ReFs Clones are used for recovery points.  

    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.

    Tuesday, March 21, 2017 9:56 PM
  • Mike, this is certainly how it worked in 2012 R2, but in our new 2016 install, the subsequent backups are not doing just the changes.  They're just as big and take just as long as the initial replica.
    Friday, March 24, 2017 5:13 AM