Antivirus software that is not cluster-aware may cause problems with Cluster Services

Antivirus software that is not cluster-aware may cause unexpected problems on a server that is running Cluster Services. For example, you may experience resource failures or problems when you try to move a group to a different node.

Warning This workaround may make a computer or a network more vulnerable to attack by malicious users or by malicious software such as viruses. We do not recommend this workaround but are providing this information so that you can implement this workaround at your own discretion. Use this workaround at your own risk.

Note Antivirus software helps protect your computer from viruses. You must not download or open files from sources that you do not trust, visit Web sites that you do not trust, or open e-mail attachments when the antivirus software is disabled.

For more information about computer viruses, click the following article number to view the article in the Microsoft Knowledge Base: Most antivirus software uses filter drivers (device drivers) that work together with a service to scan for viruses. These filter drivers reside above the file system recognizer and scan files as they are opened and closed on a local hard disk. Antivirus software may not understand the shared disk model and may not correctly allow for failover.

If you are troubleshooting failover issues or general problems with a Cluster services and antivirus software is installed, temporarily uninstall the antivirus software or check with the manufacturer of the software to determine whether the antivirus software works with Cluster services. Just disabling the antivirus software is insufficient in most cases. Even if you disable the antivirus software, the filter driver is still loaded when you restart the computer.

For more information about how to fully disable antivirus software, click the following article number to view the article in the Microsoft Knowledge Base: Even if you are not monitoring the shared disk, the filter drivers are still loaded and may affect the operation of the cluster.

You can run antivirus software on a SQL Server cluster. However, you must make sure that the antivirus software is cluster-aware. Contact your antivirus software vendor about cluster-aware versions and interoperability.

Additionally, you should exclude the following file system locations from virus scanning on a server that is running Cluster Services:

• The path of the \mscs folder on the quorum hard disk. For example, exclude the Q:\mscs folder from virus scanning.
• The %Systemroot%\Cluster folder.
• The temp folder for the Cluster Service account. For example, exclude the \clusterserviceaccount\Local Settings\Temp folder from virus scanning.

For more information about running antivirus software on servers that are running SQL Server, click the following article number to view the article in the Microsoft Knowledge Base: