Improving Performance of MS-DOS Database Applications

ID: Q219022

The information in this article applies to:

Microsoft BackOffice Small Business Server versions 4.0, 4.5

IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information about how to do this, view the "Restoring the Registry" Help topic in Regedit.exe or the "Restoring a Registry Key" Help topic in Regedt32.exe.

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: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it. If you are running Windows NT, you should also update your Emergency Repair Disk (ERD).

Perform the following steps to disable opportunistic locking and caching of open files:

Start Registry Editor (Regedt32.exe) and go to the following subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters

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

Shut down and restart the computer.

MORE INFORMATION

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

Q102967 REG: Server Service Entries, PART 1

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

Q124916 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:

Q138365 How the Autodisconnect Works in Windows NT

Additional query words: smallbiz

Keywords :
Version : winnt:4.0,4.5
Platform : winnt
Issue type : kbprb