Improving Performance of MS-DOS Database Applications (219022)


The information in this article applies to:

  • Microsoft BackOffice Small Business Server 4.0
  • Microsoft BackOffice Small Business Server 4.5
This article was previously published under Q219022

IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

When you use older MS-DOS-based database applications with a Windows NT or Small Business Server (SBS) network, you may encounter various errors such as:
The file is in use

The file is already open

Unable to write to drive X:

The network drive X: is no longer available

RESOLUTION

These older MS-DOS-based database application engines were not developed with the file locking mechanisms that Windows NT enables by default. These settings are used to improve performance of Windows NT-aware applications, but can have different results with applications that do not understand them. The best solution is to upgrade the application to one that is compatible with Windows NT or SBS. If it is not possible to upgrade the application, there are changes in the registry that could improve the performance. These registry entries will turn off the use of opportunistic file locking and the caching of files previously open but now closed, and will prevent the networking portion from closing a workstation session that it thinks has timed out.

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.

Perform the following steps to disable opportunistic locking and caching of open files:
  1. Start Registry Editor (Regedt32.exe) and go to the following subkey:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters

  2. On the Edit menu, click Add Value and add the following:

    Value Name: EnableOplocks
    Data Type: REG_DWORD
    Data: 0

    Value Name: CachedOpenLimit
    Data Type: REG_DWORD
    Data: 0

    Value Name: autodisconnect
    Data Type: REG_DWORD
    Data: ffffffff

  3. Shut down and restart the computer.

MORE INFORMATION

For additional information about EnableOplocks, please see the following article(s) in the Microsoft Knowledge Base:

102967 REG: Server Service Entries, PART 1

For additional information about CachedOpenLimit, please see the following article(s) in the Microsoft Knowledge Base:

124916 Some Client Applications Fail When Writing to Windows NT

For additional information about Autodisconnect, please see the following article(s) in the Microsoft Knowledge Base:

138365 How the Autodisconnect Works in Windows NT

Modification Type:MajorLast Reviewed:11/21/2003
Keywords:kbprb KB219022
©2003 Microsoft Corporation. All rights reserved.