Slow Network Performance with Service Pack 4, 5, 6, or 6a

• Microsoft Windows NT Server versions 4.0 SP4, 4.0 SP5, 4.0 SP6, 4.0 SP6a
• Microsoft Windows NT Workstation versions 4.0 SP4, 4.0 SP5, 4.0 SP6, 4.0 SP6a
• Microsoft Windows NT Server, Enterprise Edition versions 4.0 SP4, 4.0 SP5, 4.0 SP6, 4.0 SP6a

SYMPTOMS

Network performance may be sluggish after you apply Windows NT 4.0 Service Pack 4, 5, 6, or 6a.

CAUSE

A change was made to the Rdr.sys file in Windows NT 4.0 Service Pack 4 to fix a problem with a handle being invalidated when a dismount occurs. This may cause additional network traffic, which may degrade performance.

RESOLUTION

A supported fix that corrects this problem is now available from Microsoft, but it has not been fully regression tested and should be applied only to systems experiencing this specific problem. If you are not severely affected by this specific problem, Microsoft recommends that you wait for the next Windows NT 4.0 Service Pack that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp

   Date        Time     Size      File name   Platform
   ---------------------------------------------------
   12/23/1999  03:24p   509,392   Rdr.sys     Alpha
   12/23/1999  03:25p   265,104   Rdr.sys     I386 

STATUS

Microsoft has confirmed this to be a problem in Windows NT 4.0 Service Pack 4, 5, 6 and 6a.

MORE INFORMATION

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).

Dismounting is something we do at the file system level after we've performed direct input and output operations on, or retrieve information about, a floppy disk drive, hard disk drive, tape drive, or CD-ROM drive.

The default behavior has been changed to the behavior that existed before Windows NT 4.0 Service Pack 4 for network activity. If this fix causes a problem, you can change the new default behavior by following these steps:

1. Start Registry Editor (Regedt32.exe).



2. Locate the following key in the registry:




HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Rdr\Parameters

3. On the Edit menu, click Add Value, and then add the following registry value:




Value Name: FileSystemControlFilter
Data Type: REG_DWORD
Value: 0 or 1

Note that a setting of 0 disables the filter, which is the old behavior. A setting of 1 filters FSCTL_IS_VOLUME_MOUNTED, which is the new behavior and is the default.


4. Quit Registry Editor.

Additional query words:

Keywords : kbbug4.00 kbfix4.00
Version : winnt:4.0 SP4,4.0 SP5,4.0 SP6,4.0 SP6a
Platform : winnt
Issue type : kbbug