When you enable the AlwaysOn Availability Groups feature or SQL Server failover cluster in Microsoft SQL Server 2012, you may encounter a memory leak, and you may experience slow performance. When you check the records in the sys.dm_os_tasks table, you may find many records.
Additionally, when this issue occurs, the records in sys.dm_os_tasks table increase each day. And, the physical I/O rate may slightly increase each day.
The issue was first fixed in the following cumulative update of SQL Server.
Cumulative Update 6 for SQL Server 2012 SP1 /en-us/help/2874879
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. Check out the latest cumulative updates for SQL Server:
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.
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, submit a request to 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 website:
http://support.microsoft.com/contactus/?ws=supportNote 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.
PrerequisitesTo apply this hotfix, you must have SQL Server 2012 installed.
Registry informationYou do not have to change the registry after you apply this hotfix.
Hotfix replacement informationThis hotfix does not replace any other hotfixes.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.