Cause of Database Mirroring automatic failover

  • Hi,

    Today morning our prod database has been failed over from principal to mirror....Please let me know what might be the reason....

    Here are the errors..

    Principal server error log :

    2013-06-19 01:26:27.180spid27sSQL Server has encountered 1 occurrence(s) of cachestore flush for the 'Object Plans' cachestore (part of plan cache) due to some database maintenance or reconfigure operations.

    Witness server log :

    6/19/2013 1:30:18 AM, SQL Server Error Log on xxxxxxx is Warning.

    SQL Server instance xxxxxx recorded 1 error log message requiring attention.

    The message are shown below in context (if applicable):

    Warning6/19/2013 1:26:20 AMspid10sError: 1479, Severity: 16, State: 1.

    OK6/19/2013 1:26:20 AMspid10sThe mirroring connection to "TCP://xxxx.ds.xxxx.com:9030" has timed out for database "xxxxxx" after 10 seconds without a response. Check the service and network connections.

    environment :

    Sql server 2005 SP3 standard edition

    windows server 2003

    Database mirroring configured with HA

    Please let me know if you need more details....

  • Just like the error states, the witness couldn't reach the principal for 10 seconds.

    This could happen for any number of reasons. An extremely high work load that causes the server to be come unavailable, a network disruption lasting longer than 10 seconds, drop network packages, vm issues, DNS issue, etc.

    In my past life, we had the witness on a vm, which was over provisioned. So when the server physical server running the VM went into overdrive, it started causing issues. As a temporary fix, we increased the duration of the mirroring timeout from 10 to 30. Once we had a new machine, we moved the VM, which resolved a number of the lost packets and sudden connection issues that we saw.

    Fraggle.

  • thanks for the response....

    but i dont see much activity in the instance...and it occured around 1:20 AM....

  • Robin35 (6/19/2013)


    Principal server error log :

    2013-06-19 01:26:27.180spid27sSQL Server has encountered 1 occurrence(s) of cachestore flush for the 'Object Plans' cachestore (part of plan cache) due to some database maintenance or reconfigure operations.

    proccache has been flushed/remove. It could because of server / database level configuration change or memory pressure.

    Some times, if principal is running with low resources like cpu,memory (in your case of memory pressere) there is a possiblity of principal's low response to witness that may do failover.

Viewing 4 posts - 1 through 3 (of 3 total)

You must be logged in to reply to this topic. Login to reply