DFS is commonly used to ensure that users connect to the optimal CacheDrive based on their geographical location, available network access, etc.  One potential problem is that an improperly setup DFS configuration could cause the target share to change while a file is open.

Consider a setup consisting of two CacheDrives, one in office A and the other in office B.  A typical DFS setup would have users connect to CacheDrive A when in office A and CacheDrive B when he is in office B.

The problem arises when DFS is configured in such a way that a user in office A may suddenly be switched to CacheDrive B.  For example, if the two offices are connected via VPN, the DFS changeover may be due to failover.

If this happens when the user has a file open in CacheDrive A, he may suddenly find himself unable to write to the file because the file is locked.  The reason for this is that the DFS target share change has him accessing the same file on another CacheDrive, while the lock is based on his access on the initial CacheDrive.

To prevent this from happening, DFS must be configured to prevent target share switching unless absolutely necessary.  Ideally, the file would be closed before the target switch happens to properly maintain lock integrity.

Morro Audit can be used to determine which CacheDrive was being used to serve the file when the issue appeared.  If Audit shows that the serving CacheDrive changed while the file was open, then it's a good indication that the switchover was the cause of the issue.