Unsupported Reparse Point in a Replicated Folder

[mkaec]

I've been switching some servers over from Windows Server Backup to VAW. The servers have Windows deduplication enabled and replicate to another server via DFS-R. Some of the servers have been running for years with Windows Server Backup backing them up. After installing VAW, the servers start recording events about reparse points.

The DFS Replication service encountered an unsupported reparse point in a replicated folder. This reparse point will not be replicated because the replication of this type of reparse point is not supported by the DFS Replication service.

On the one hand, this seems normal. Windows dedup uses reparse points, and if a file is complete duplicate of another, then just a single reparse point will exist for the second file. And DFS Replication was designed to not support reparse points because the deduplication use case didn't exist at the time. One would expect the behavior that is being observed. But, I don't understand why this starts up after switching from WSB to VAW.

[HannesK]

Hello,
the switch to VAW could just be a coincidence. As you say, it's expected behavior, I'm not sure how to help.

Best regards,
Hannes

[mkaec]

It's happened too many times to be a coincidence (5 times), and starts the day after VAW is installed. Either VAW is changing something or WSB is doing something special to avoid the problem. You may not be able to help, but I posted on the chance that someone has seen this before or has a deeper understanding of VAW and WSB than I do.

I do notice a 6th server running Windows Server 2019 hasn't logged this event. The other 5 are Server 2012 R2. Fingers crossed that the problem will go away after they are upgraded later this year. But since it's just the 1 server that doesn't have the problem, that could be the coincidence.

[mkaec]

I recently switched a Windows Server 2019 system from Windows Server Backup to VAW and the 4406 reparse point problem developed on the system. I uninstalled VAW, set WSB back up, and restarted the server and the problem stopped.

I didn't install VAW's special CBT driver. Does basic VAW install any sort of file system filter driver? If it does, I'm thinking maybe there could be a conflict with the DFS-R or data deduplication filter driver.

[HannesK]

Hello,
Hmm, that sounds odd.

Investigating with support sounds like the only realistic option here (please post the case number). And are you using V6? Because there won't be fixes for V5 anymore.

Best regards,
Hannes

[mkaec]

Something interesting has happened. I had been battling the 4406 events, repairing the sync of 10-30 files each day. I set up a test system for the planned Veeam support case. I had replicated that installing VAW triggered the problem, and removing VAW (and rebooting) stabilized the system. I even recorded this video. Then the next day I went to record a new video. I recorded the one I shared here to be shared here. But I wanted to include some system-specific data in the video I shared with support. But when I tried to record the new video, I couldn't replicate the problem anymore. It turned out that the Mar 2023 Windows Updates had installed on the test system the night before. So, I waited for them to install onto the production systems to see what would happen. My daily battles with DFS-R 4406 events stopped after that. There were 3 occurrences on 3/21/2023, but none since then. I'm inclined to conclude that Microsoft fixed some bug that VAW happened to be triggering. The 3 extra occurrences don't quite jive with that. But things have been stable for a week now.

[HannesK]

thanks for reporting back about the Microsoft update. That can help other users!

[mkaec]

It looks like the Windows update didn't actually have anything to do with the resolution. Recently, I updated the systems to VAW 6.0.2. The next day, the 4406 events were back. Installing a Windows update happens to cause reboot of the system. After the return of the 4406 events, I rebooted the systems and the events subsided again. Rebooting is going to become standard SOP for me when updating VAW, even when VAW setup doesn't ask me to.