DFS and Offline Files – A Match Made In Hell

If you are using DFS and Offline Files in your organisation then you have probably run in to the problem (or if you are reading this then perhaps you are still experiencing it!) whereby your users will ‘randomly’ disconnect and lose access to all DFS shares for no apparent reason.

If you are using offline files then this is most likely the cause of the DFS file shares going offline. You can test this theory by doing the following:

  • Open up explorer and navigate to \\domain.com\dfsroot (default is \\domain.com\share)
  • Turn on ‘work offline’ mode – in Windows 8 the option is in the Home tab –> Each access –> work offline
  • All your shares will disappear

The reason for this is that the “Offline Files feature does not distinguish DFS paths from UNC paths. This can cause the Vista / Windows 7 client to interpret the entire namespace as unavailable if a target is down when a Vista / Windows 7 client attempts to access it”

This will cause you to get errors such as:

Windows cannot access \\domain.com\share\share1

OR

Drive:\ is unavailable. If the location is on this PC, make sure the device or drive is connected or the disc is inserted, and then try again. If the location is on a network, make sure you’re connected to the network or Internet, and then try again. If the location still can’t be found, it might have been moved or deleted

The solution to this problem is to use the FQDN/NetBIOS name for your DFS shares.

For example, if your offline files drive is: \\domain.com\share\home

Simply make all your other shares: \\domain\share\share1

The reason this fixes it is because Windows sees \\domain and \\domain.com as two different paths completely so when your offline files share goes in to offline mode, the other shares still continue to work in online mode. Annoying but at least it’s an easy fix and as far as I can tell, there are no issues with using the NetBIOS name.