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

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.

Service pack information

To resolve this problem, obtain the latest service pack for Windows Server 2003. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

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: 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 available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

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

Windows Server 2003, x64-based versions

Windows Server 2003, Itanium-based versions

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Windows Server 2003 Service Pack 2.

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

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