Deadlock condition may occur when a large number of DFS clients connect to a shared folder for the first time

When many Distributed File System (DFS) clients connect to a server and access a shared folder for the first time, you may find that a deadlock condition occurs in the server message block (SMB) redirector component or in the Terminal Services redirector component. Therefore, the server does not return a referral to the DFS client, and the DFS client cannot connect to the shared folder.

For example, a deadlock condition in the Terminal Services redirector component may result when many DFS clients connect to the server in a Terminal Services session and access different \\ServerName\ShareName shares, where an entry does not exist for any one of the shares in the DFS referral cache.

This problem may occur if both the following conditions are true:

• The number of network file access requests is larger than the number of available critical worker threads.
• The network file access requests are for \\ServerName\ShareName shares that are accessed by the DFS client for the first time. That is, share entries do not exist in the DFS referral cache.

The DFS client (Mup.sys) posts network file access requests to the critical work queue on the server. Because the DFS client does not throttle work items, a deadlock condition may occur in situations where the redirector components require worker threads to complete the transport connection operations, and the worker threads are exhausted by the DFS client.

To resolve this issue, 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:

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

This hotfix requires Windows Server 2003.

Restart requirement

You must restart your 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) 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.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section of this article. This problem was corrected in Windows Server 2003 Service Pack 1.

For more information about DFS in Windows Server 2003, visit the following Microsoft Web site: