Deduplicating MBS volume directly RRS feed

  • Question

  • When DPM 2019 came out on Server 2019, we quickly moved to it and deduplicating the MBS volume directly as the overhead and issues related to running DPM in Hyper-V and deduplication on the host caused massive fragmentation and horrible performance.  At the time I couldn't find any information on the support of that and contacted our Microsoft rep who provided us this response (Support Engineer on 4/2/2019): "Yes , It is supported to run deduplication directly on Refs volume in server 2019 and Technically it should be supported on DPM."

    I recently came back to the setup documentation to check for any new recommendations on how to setup DPM 2019 and found this new notice: "DPM does not support deduplication on ReFS disk used for MBS backups."

    With that, I'm guessing the setup we're running is not supported; however, what are the reasons?  What issues are there with doing this or problems that may arise from doing it?

    As mentioned, I've been doing this on a few DPM boxes and backups have been running fine, deduplication has been keeping pace, restores have ran, and overall is more stable and performant than doing the multiple 1TB VHDx, DPM in Hyper-V, Storage Space inside the VM, so I'm looking for what should we be on the lookout for or why should we go back to the old way?
    Monday, August 12, 2019 1:14 PM

All replies

  • Hello,

    Many times when Microsoft states "not supported" it often means that they have simply not tested/verified it.

    As you've noticed, running "unsupported scenarios" can work just fine, and sometimes it can even produce better results, but if something does eventually happen you'll be without any support, so this is a gamble you'll have to take.

    I don't have a straight answer to your question to why Microsoft has chosen this way, however you can request feedback over the DPM uservoice over here:

    Best regards,

    Blog: LinkedIn:

    • Proposed as answer by Leon Laude Tuesday, August 13, 2019 8:26 PM
    Monday, August 12, 2019 2:00 PM
  • I'm hoping that is the case as I haven't seen any specific negatives yet; I'm just curious if there's some actual incompatibility and not simply an un-tested scenario.  Though, I suppose they would have probably worded it as incompatible and not simply unsupported.
    Monday, August 12, 2019 9:27 PM
  • Write down your scenario in the uservoice link I provided above, and ask the DPM product team if they could possibly test it and check whether it could be supported.

    Blog: LinkedIn:

    Tuesday, August 13, 2019 7:02 AM
  • And done:
    Tuesday, August 13, 2019 11:58 AM
  • Great, I voted :-)

    Blog: LinkedIn:

    Tuesday, August 13, 2019 12:14 PM