Microsoft distributes Microsoft SQL Server 2012 fixes as one downloadable file. Because the fixes are cumulative, each new release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2012 fix release.
Consider the following scenario:
You have an instance of Microsoft SQL Server 2012 that has the AlwaysOn Availability Groups feature enabled.
You add several availability groups (AGs) to the instance.
You join a secondary replica into these AGs two times.
In this scenario, the secondary databases in the secondary replica may be in "unknown" state. Additionally, the data movements stop, and the secondary databases cannot be accessed when the corresponding primary replica is disconnected.
Cumulative update information
SQL Server 2012
The fix for this issue was first released in Cumulative Update 1 for SQL Server 2012. For more information about how to obtain this cumulative update package for SQL Server, click the following article number to view the article in the Microsoft Knowledge Base:
Note Because the builds are cumulative, each new fix release contains all the hotfixes and all the security fixes that were included with the previous SQL Server fix release. We recommend that you consider applying the most recent fix release that contains this hotfix. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
2692828 The SQL Server 2012 builds that were released after SQL Server 2012 was released
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
To work around this issue, bring the secondary databases online, and then rejoin the secondary replica into the AGs.
For more information about the AlwaysOn Availability Groups feature, visit the following Microsoft Developer Network (MSDN) website: