Mirroring connection has timed out

Question

Hi All,

We've mirroring setup cross geography. I've noticed the below error in the SQL errorlog of the Principal server for one or the other database at a given time. However, the error is not logged at once for all the databases.

The mirroring connection to "TCP://<MIRROR_SERVER>:5022" has timed out for database "<DB_NAME>" after 300 seconds without a response.  Check the service and network connections.

We checked and couldnt find any network issue. Also, if it would have been a network issue, it should have thrown error for all the databases mirrored from that server, but this doesn't happen in our case.

We checked the status of database and couldnt find any blocking or connection time out issues. The database is accessible easily and the server is also working without any load.

Request you to help in finding the issue and the resolution of the same.

OS: Windows Server 2008 R2 Enterprise Edition
SQL: SQL Server 2008 R2 Enterprise Edition SP1 CU1&2

Thanks
Mayur Kashikar

Answer 1

DBM will only do automatic failover if you are using high-safety with a witness and things are synchronized. If that isn't your setup and/or you were not synchronized, no DBM would not fail over to the mirror.

What did you look at to determine you have no network issue? SQL is usually right in this case. What else was going on at the time? What does the Event log say? Have you run network traces? etc etc

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Allan Hirt Blog: http://www.sqlha.com/blog Coming in 2013: Mission Critical SQL Server 2012 - the followup to Pro SQL Server 2008 Failover Clustering

Answer 2

Thanks Allan!

However, you probably missed out one statement. I said "Also, if it would have been a network issue, it should have thrown error for all the databases mirrored from that server, but this doesn't happen in our case."

We got the Network checked by the IT team internally and didnt find any issue during this interval.

Event Viewer didn't have any errors too!

Answer 3

This could be some network contention happening during that time - any SAN level backups / files copy might use network bandwidth same thing happened to us last years and we fix the error by moving backup scheduled to different time  

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