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© Rakhesh Sasidharan

DFS Namespaces missing on some servers / sites

This is something I had sorted out for one of our offices earlier. Came across it for another office today and thought I should make a blog post of it. I don’t remember if I made a a blog post the last time I fixed it (and although it’s far easier to just search my blog and then decide whether to make a blog post or not, I am lazy that way :)).

Here’s the problem. We use AppV to stream some applications to our users. One of our offices started complaining that AppV was no longer working for them. Here’s the error they got:

cderror

I logged on to the user machine to find out where the streaming server is:

Checked the Event Logs on that server and there were errors from the “Application Virtualization” source along these lines:

So I checked the DFS path and it was empty. In fact, there was no folder called “Content” under “\\domain.com\dfs” – which was odd!

I switched DFS servers to that of another location and all the folders appeared. So the problem definitely was with the DFS server of this site.

From the DFS Management tool I found the namespace server for this site (it was the DC) and the folder target (it was one of the data servers). Checked the folder target share and that was accessible, so no issues there. It was looking to be a DFS Namespace issue.

Hopped on to the DFS and checked “C:\DFSRoots\DFS”. It didn’t have the “Content” folder above – so definitely a DFS Namespace issue!

I ran dfsdiag and it gave no errors:

So I checked the Event Logs on the DC. No errors there. Next I restarted the “DFS Namespace” service and voila! all the namespaces appeared correctly.

Ok, so that fixed the problem but why did it happen in the first place? And what’s there to ensure it doesn’t happen again? The site was restarted yesterday as part of some upgrade work so did that cause the namespaces to fail?

I checked the timestamps of the DFS Namespace entries (these are from source “DfsSvc” in “Custom Views” > “Server Roles” > “File Server”). Once the namespaces were ready there was an entry along the following lines at 08:06:43 (when the DC came back up from the reboot):

No errors there. But where does the DC get its name spaces from? This was a domain DFS so it would be getting it from Active Directory. So let’s look at the AD logs under “Applications and Services Logs” > “Directory Service”. When the domain services are up and running there’s an entry from the “ActiveDirectory_DomainService” source along these lines:

On this server the entry was made at 08:06:47. Notice the timestamp – it occurs after the “DFS Namespace” service has finished building namespace! And therein lies the problem. Because the Directory Services took a while to be ready, when DFS was being initialized it went ahead with stale data. When I restarted the service later, it picked up the correct data and sorted the namespaces.

I rebooted the server a couple more times but couldn’t replicate the problem as the Directory Service always initialized before DFS Namespace. To be on the safe side though I set the startup type of “DFS Namespace” to be “Automatic (Delayed)” so it always starts after the “Directory Service”.