You experience poor performance on a Windows Server 2003 R2-based computer that is running a server for NFS when the NFS server tries to look up mapping for an unmapped user

Consider the following scenario,

• In a domain environment, you install Microsoft Services for Network File System (NFS) on a Windows Server 2003 R2-based computer.
• You create an NFS share on the Windows Server 2003 R2-based computer.
• On a Linux-based or UNIX-based computer, you create a user account that does not have a Windows mapping in the Active Directory directory service. In other words, the unmapped user account does not have UNIX user identifications (UIDs) or UNIX group identifications (GIDs) in Active Directory.
• You mount the NFS share on an NFS client.
• You use the unmapped user account to access the NFS share.

In this scenario, you experience poor write performance on the NFS server when the NFS server tries to look up mapping for unmapped users.

When you use an unmapped account to access the NFS share, this generates LDAP lookup requests to Active Directory. When this behavior occurs on every NFS RPC packet, it has a disastrous effect on system performance. This problem does not occur as long as an NFS RPC packet has a UID or a GID that is available in Active Directory.

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 R2 SP1 or Windows Server 2003 R2 SP2 to be installed on the computer.

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 item in Control Panel.

Windows Server 2003 with Service Pack 1, x86 version

Windows Server 2003 with Service Pack 2, x86 version

Windows Server 2003, x64 version

Windows Server 2003 with SP2, x64 version

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

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.