The failover operation takes a long time to fail over a shared disk resource that is located on a cluster node of a Windows Server 2008-based failover cluster if many snapshots are saved on the shared disk

Consider the following scenario:

• You install the Failover Clustering feature on some computers that are running Windows Server 2008.
• Many snapshots are created on a shared disk that is located on one of the cluster nodes.
• You try to fail over the shared disk resource to another node.

In this scenario, the failover operation takes a long time to fail over the shared disk resource to another node. For example, the operation takes 15 or 20 minutes to finish.

Note The issue usually occurs on a clustered file server.

Windows Server 2008 supports the FSCTL_LOCK_VOLUME control code for some new application compatibility features.

This problem occurs because these new application compatibility features require lots of I/O read requests before the failover operation is started. These read requests depend on the snapshot volume. Therefore, the failover operation takes a long time to fail over the shared disk resource.

This hotfix introduces a new flag for Volume Shadow Copy Service (VSS). With this new flag, the VSS service can optimize the failover operation to reduce the number of I/O read requests.

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 the problem described in this article. 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

To apply this hotfix, the computer must be running one of the following operating systems:

• Windows Server 2008
• Windows Server 2008 Service Pack 2 (SP2)

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfix.

File information

Important Windows Vista hotfixes and Windows Server 2008 hotfixes are included in the same packages. However, hotfixes on the Hotfix Request page are listed under both operating systems. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows Vista/Windows Server 2008" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.

• The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows Server 2008" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are extremely important to maintain the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.

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.

For all supported x86-based versions of Windows Server 2008

For all supported x64-based versions of Windows Server 2008

For all supported Itanium-based versions of Windows Server 2008

To work around the issue, stop the snapshot operations on the disk.

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

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

Additional file information for Windows Server 2008

Additional files for all supported x86-based versions of Windows Server 2008

Additional files for all supported x64-based versions of Windows Server 2008

Additional files for all supported Itanium-based versions of Windows Server 2008

For more information about the FSCTL_LOCK_VOLUME control code, visit the following Microsoft Developer Network Web site: