Shared file access is delayed if the file is open on another computer

If you try to open a file on a computer that is running Windows NT over the network and the file is open on another client computer that has sharing restrictions, there is a delay of approximately one second before the sharing violation error message is returned. If the client application is accessing a number of files on the server, this delay may become significant. These symptoms can be easily seen with any multi-user, file-based application, such as the Jet database engine that has shared database files.

NOTE: This behavior is not observed when accessing files on LAN Manager or Windows for Workgroups shares.

This issues occurs because an optimization in the Windows NT Server service delays returning a status to the client while it tries to internally resolve the sharing violation.

To resolve this issue, it may be best to turn off this optimization. To do so, you must make the following two registry additions.

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

1. Start Registry Editor.
2. Locate the following registry key:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
3. Add the following information:
   Value Name: SharingViolationDelay
   Data Type: REG_DWORD
   Data: 0 (Default: 200)
   
   Value Name: SharingViolationRetries
   Data Type: REG_DWORD
   Data: 0 (Default: 5)
4. Quit Registry Editor, and then restart the computer.

If the Server service receives a request for file that is already open, it receives a sharing violation from the local server. The service then waits for a short period before trying to access the file again. This process is repeated a number of times, internally to the server, to try to resolve the problem before returning to the client.

This feature is controlled by the following two registry values:

• SharingViolationDelay
  
  Default 200 (msec)
  
  This is the period of time that the server waits between retries. If it is set too low, the server receives multiple sharing violations. If it is set too high, the Server Message Block (SMB) response to the client might be delayed, thereby reducing performance.
• SharingViolationRetries
  
  Default 5
  
  This is the number of times that the server retries an SMB requested operation if it receives a sharing violation from the local server's file system. Operations that are affected by this include open, rename, and delete. This minimizes network traffic because if the server can resolve the sharing violation locally, the remote clientdoes not have to retry the operation.