MS Windows Oplocks and Caching Controls
There is a known issue when running applications (like Norton Antivirus) on a Windows 2000/ XP
workstation computer that can affect any application attempting to access shared database files
across a network. This is a result of a default setting configured in the Windows 2000/XP
operating system. When a workstation
attempts to access shared data files located on another Windows 2000/XP computer,
the Windows 2000/XP operating system will attempt to increase performance by locking the
files and caching information locally. When this occurs, the application is unable to
properly function, which results in an “Access Denied”
error message being displayed during network operations.
All Windows operating systems in the NT family that act as database servers for data files
(meaning that data files are stored there and accessed by other Windows PCs) may need to
have oplocks disabled in order to minimize the risk of data file corruption.
This includes Windows 9x/Me, Windows NT, Windows 200x, and Windows XP.
If you are using a Windows NT family workstation in place of a server, you must also
disable oplocks on that workstation. For example, if you use a
PC with the Windows NT Workstation operating system instead of Windows NT Server, and you
have data files located on it that are accessed from other Windows PCs, you may need to
disable oplocks on that system.
The major difference is the location in the Windows registry where the values for disabling
oplocks are entered. Instead of the LanManServer location, the LanManWorkstation location
may be used.
You can verify (change or add, if necessary) this registry value using the Windows
Registry Editor. When you change this registry value, you will have to reboot the PC
to ensure that the new setting goes into effect.
The location of the client registry entry for oplocks has changed in
Windows 2000 from the earlier location in Microsoft Windows NT.