The Windows Server 2003 redirector component limits the number of files that can be open at the same time to 16,383, even when multiple connections are pooled in DFS (913835)


The information in this article applies to:

  • Microsoft Windows Server 2003, Datacenter Edition for Itanium-based Systems
  • Microsoft Windows Server 2003, Enterprise Edition for Itanium-based Systems
  • Microsoft Windows Server 2003, Datacenter x64 Edition
  • Microsoft Windows Server 2003, Enterprise x64 Edition
  • Microsoft Windows Server 2003, Standard x64 Edition
  • Microsoft Windows Server 2003, Datacenter Edition
  • Microsoft Windows Server 2003, Enterprise Edition
  • Microsoft Windows Server 2003, Standard Edition
  • Microsoft Windows Server 2003, Web Edition
Important This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows registry

SYMPTOMS

Sometimes, multiple connections to a server are pooled and forwarded by using the delegation level of security impersonation. For example, Distributed File System (DFS) uses such a configuration. However, the redirector component in Microsoft Windows Server 2003 limits the number of files that can be open at the same time to 16,383 per connection. In this scenario, you may have to increase the number of connections to handle all the potential open files from the pooled connections.

Note You may expect the 16,383 open-file limit to be applied on a per-client basis instead of on a per-connection basis.

RESOLUTION

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.Warning The following procedure enables redirector multiplexing on the server. Redirector multiplexing duplicates all network connection structures. This duplication may greatly increase the load on a file server. Therefore, the following procedure may overburden the server and greatly decrease performance.

To resolve this issue, install the hotfix that is described later in the "Resolution" section. Then, add a DWORD value that is named "MultiUserEnabled" to the following registry subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MRxSmb\Parameters

Set this DWORD value to 1.

After you create this DWORD value, the redirector component will use multiplexing mode. In multiplexing mode, connections are allocated on a per-client basis instead of on a per-connection basis. Multiplexing enables each client that connects through the forwarding server to open as many as 16,383 files. Without this DWORD value, the redirector component enables a total of only 16,383 open files for all clients.

Additionally, you must disable client-side caching by setting the CscEnabled value to 0 in the same registry subkey.

To add these registry entries, follow these steps:
  1. Click Start, click Run, type regedit in the Open box, and then click OK.
  2. Locate and then click the following registry subkey:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MRxSmb\Parameters

  3. On the Edit menu, point to New, and then click DWORD Value.
  4. Type MultiUserEnabled for the name of the DWORD value, and then press ENTER.
  5. Right-click MultiUserEnabled, and then click Modify.
  6. In the Value data box, type 1, and then click OK.
  7. Right-click CscEnabled , and then click Modify.
  8. In the Value data box, type 0, and then click OK.
  9. Exit Registry Editor, and then restart the computer.

Hotfix information

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.

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

http://support.microsoft.com/contactus/?ws=support

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.

Prerequisites

You must be running Windows Server 2003 SP1 to install this hotfix.

Note x64-based versions of Windows Server 2003 do not require this service pack.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.Windows Server 2003, x86-based versions
File nameFile versionFile sizeDateTimePlatform
Mrxsmb.sys5.2.3790.2630436,73601-Feb-200602:35x86
Windows Server 2003, x64-based versions
File nameFile versionFile sizeDateTimePlatform
Mrxsmb.sys5.2.3790.2630784,89601-Feb-200609:20x64
Windows Server 2003, Itanium-based versions
File nameFile versionFile sizeDateTimePlatform
Mrxsmb.sys5.2.3790.26301,168,38401-Feb-200609:22IA-64

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

MORE INFORMATION

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

MORE INFORMATION

Technical support for Windows x64 editions

Your hardware manufacturer provides technical support and assistance for Microsoft Windows x64 editions. Your hardware manufacturer provides support because a Windows x64 edition was included with your hardware. Your hardware manufacturer might have customized the Windows x64 edition installation with unique components. Unique components might include specific device drivers or might include optional settings to maximize the performance of the hardware. Microsoft will provide reasonable-effort assistance if you need technical help with your Windows x64 edition. However, you might have to contact your manufacturer directly. Your manufacturer is best qualified to support the software that your manufacturer installed on the hardware.

For product information about Microsoft Windows XP Professional x64 Edition, visit the following Microsoft Web site:

http://www.microsoft.com/windowsxp/64bit/default.mspx

For product information about Microsoft Windows Server 2003 x64 editions, visit the following Microsoft Web site:

http://www.microsoft.com/windowsserver2003/64bit/x64/default.mspx

Modification Type:MajorLast Reviewed:2/7/2006
Keywords:kbQFE kbExpertiseAdvanced kbHotfixServer KB913835 kbAudITPRO
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