Third party storage replication software and Server 2016 issue’s with S2D

Hi All, recently I encountered some issue’s with third party software to replicate VMs from an old Windows Server 2012 cluster to a brand new Windows Server 2016 S2D Cluster, were it turned out that the third party software was not fully supported on Windows Server 2016 although they claimed to be. I know you could use Share Nothing live Migration but in this case that was not possible so we had to look for third party software.

In this example I encountered two issue’s when using Storage Spaces Direct and the ReFS file system (which is a hard requirment with S2D) together with the replication software.

Issue 1

So my first issue was with the agent that you install on a Windows Server 2016 Hyper-V host to be able to migrate servers from a source VM to a Hyper-V Storage Space Direct cluster as destination. After a push from the console or a manual installation the agent service would not start. After starting it crashes with a .net error. Well that seems pretty simpel and straight forward… do you really need a blog for that. That’s true but the next issue is not directly noticeable. In the end it turned out that the service could not start because it could not work with ReFS.

Issue 2

After starting of the service failed, the vendors tech support provided a work arround, and since there was a deadline pushing we took the work around and left the agent running and migrated the VMs through the work around but that’s not what this blog is about.

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DPM 2016 Modern Backup Storage and Deduplication performance issue

Modern Backup Storage and Deduplication

One of the great features of Hyper-V in combination with a virtual DPM server was the ability to use deduplication. On the Hyper-V host you have a volume which is enabled for dedup where you place your .vhdx files on that serves as backup storage for the virtual DPM server. This way you can safe a lot of disk space.

Since DPM 2016 you can use Modern Backup Storage (MBS). With MBS you can use Storage Spaces to create a volume with shares that you present to DPM. Now I hear you thinking hey, we can enable Dedup on that volume and let DPM backup data to that volume and it get’s deduped so we can use a physical machine to… Unfortunately not, because MBS requires ReFS as file system on the disk, Dedup is ruled out because it is not yet supported and not available on ReFS volumes.

So we still need a physical Hyper-V host with an NTFS volume for the .vhdx files with dedup enabled. In the VM we create the storage space with a virtual disk and a ReFS volume and you are ready to cruise with your DPM server.

The setup

So the situation above also discribes the setup a bit. In short we have a physical host that has storage for the virtual DPM server. In this case it was a disk enclosure attached to the host with several SATA disks that we added to a storage space. On top of the storage space a mirrored volume was created to place the backup .vhdx files on. The host takes care of the deduplication of the backup data inside the .VHDX files. The vm takes care of the Storage Space and DPM.

The physical host has to take care of some dedub jobs like optimizing, garbage collection and scrubbing. These jobs cost a big amount of IO and a large amount of

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