If a user tries to access a READ PERM DB file residing on a Windows NT server machine where DB2 Datalinks is installed using a shared drive using a valid token, the file opens as expected. However, after that, subsequent open requests using the same token do not actually reach the server, but are serviced from the cache on the client. Even after the token expires, the contents of the file continue to be visible to the user, since the entry is still in the cache. However, this problem does not occur if the file resides on a Windows NT workstation.
A solution would be to set the registry entry \\HKEY_LOCAL_MACHINE\SYSTEM \CurrentControlSet\Services\Lanmanserver\Parameters\EnableOpLocks to zero on the Windows NT server. With this registry setting, whenever a file residing on the server is accessed from a client workstation through a shared drive, the request will always reach the server, instead of being serviced from the client cache. Therefore, the token is re-validated for all requests.
The negative impact of this solution is that this affects the overall performance for all file access from the server over shared drives. Even with this setting, if the file is accessed through a shared drive mapping on the server itself, as opposed to from a different client machine, it appears that the request is still serviced from the cache. Therefore, the token expiry does not take effect.