XenDesktop 5.x Broker service logs database connectivity warnings in the Event viewer in a Clustered or Mirrored SQL environment. There might not be any problems experienced by the users apart from the repeated events found in the event logs:

Warning Citrix Broker Service 1201 None The connection between the Citrix Broker Service and the database has been lost.
Information Citrix Broker Service 1200 None The connection between the Citrix Broker Service and the database has been restored.

These events could be logged at the same time indicating that the disruption if any, was very small.

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Microsoft has released a fix for the issue and is documented in FIX: Time-out error when a mirrored database connection is created by the .NET Framework data provider for SQLClient.

Note: The above documentation is not accessible as the problem was seen in Windows Server 2008 R2 SP1 and XenDesktop 5.x may not be applicable to newer versions.

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Problem Cause

These warnings are recorded when there is a disruption to the database connectivity. However, because of a certain error in the connection-retry algorithm used by SQL Provider, these events can also be recorded even when there is no apparent disruption to database connectivity.

Database Connectivity Warnings in XenDesktop 5.x

Installing the hotfix is the recommended option.

As a workaround, modify the XenDesktop Database Connection strings as shown:

Server=<SQLServerName>;Database=<DBName>;Trusted_Connection=true;Failover Partner=<SQLSrvName>;Connection Timeout=150;Min Pool Size=20