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. After a while I noticed that one of the volumes of the cluster was in redirection mode.

I also checked with powershell because the Failover Cluster Manager is not always giving the actual picture of the situation. But it’s the same there..

Fortunately this volume was still empty so I did some tests. When I failed the volume over to other nodes it was not in redirected mode. But when back on node 13 is when straight to redirection mode. Took it offline and online again but after couple of seconds it ended up in redirection mode again. Remove as CSV and added it again but still the same error. The other volumes were in use so I was not able to test with those volumes but it look like an issue with this host and not the volume.

When running a more extensive command Get-ClusterSharedVolumeState there was some more info.

So Incompatible File System Filter drivers were causing issues! File System Filter drivers are running at the kernel level and are used to monitor, modify, act to or with the file system. In the case of the software from the third party vendor it uses the filters to monitor for changes to replicate. The File System Filter that comes with this software is incompatible with ReFS and therefore causing the volume to stay in redirected mode. See the blog by Elden Christensen for more details.

So after establishing that the agent was messing with the volume I removed the agent (because it was not working anyway) and rebooted the server. When requesting the state of the volumes now with Get-ClusterSharedVolumeState we see no incompatible File System Filter error anymore.

Also the volumes report no redirection mode:

So beware wen installing third party software on agents on your S2D Hosts that the really have ReFS Support and that there File System Filter Drivers is not reported legacy. I am specifically not putting the software vendor or the product name here because I don’t want to bash them because they are delivering a really good solution but they just have an issue with ReFS. Hopefully they come up with a fix for it 🙂

Good luck!
Pascal Slijkerman

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