Microsoft KB Archive/249799

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

Article ID: 249799

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Server 4.0, Terminal Server Edition
 * Microsoft Windows NT 4.0 Service Pack 4
 * Microsoft Windows NT 4.0 Service Pack 5
 * Microsoft Windows NT 4.0 Service Pack 6
 * Microsoft Windows NT Workstation 4.0 Developer Edition
 * Microsoft Windows NT Workstation 4.0
 * Microsoft Windows NT Workstation 4.0 Developer Edition
 * Microsoft Windows NT 4.0 Service Pack 4
 * Microsoft Windows NT 4.0 Service Pack 5
 * Microsoft Windows NT 4.0 Service Pack 6

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This article was previously published under Q249799



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
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 an issue with a handle being invalidated when a dismount occurs. This may cause additional network traffic, which may degrade performance.



Windows NT Server or Workstation 4.0
A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English version of this fix should have the following file attributes or later:   Date      Time                 Size    File name     Platform -  12/23/1999  04:25p             265,104 rdr.sys       Intel 12/23/1999 04:24p             509,392 rdr.sys       Alpha

NOTE: You must install the latest Windows NT Service Pack (SP6a) to use this hotfix. Windows NT SP6 is required by Rdr.sys dependencies on SP6, which means that Rdr.sys cannot be fixed for any previous Service Pack version.

Using the hotfixed version of Rdr.sys that resolves this problem with any other service pack is not supported.

Windows NT Server 4.0, Terminal Server Edition
To resolve this problem, obtain the latest service pack for Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

152734 How to Obtain the Latest Windows NT 4.0 Service Pack



Windows NT Server or Workstation 4.0
Microsoft has confirmed that this is a problem in Windows NT 4.0.

Windows NT Server 4.0, Terminal Server Edition
Microsoft has confirmed that this is a problem in Windows NT 4.0 Service Packs 4 and 5. This problem was first corrected in Windows NT Server 4.0, Terminal Server Edition Service Pack 6.



MORE INFORMATION
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.

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 an issue, you can change the new default behavior by following these steps:  Start Registry Editor (Regedt32.exe). Locate the following key in the registry:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Rdr\Parameters

 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.

 Quit Registry Editor.</li></ol>

Additional query words: rdr.sys

Keywords: kbbug kbfix kbqfe kbhotfixserver KB249799

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