Cluster Failover Question

  • Hi,

    We have A/P cluster setup for SQL Server 2005. I have to stop the SQL Services on Active node and then Disconnect the entire company Network communication for simulating Disaster recovery.

    Here, when the entire network goes down, will the SQL Services from active node try to move to passive node? or will they stay at active node itself as the entire network is gone. I do not want to move the SQL Servcies from active node to passive node. Please advice me

    thanks

  • What is your cluster topology in relation to your network?

    Is your cluster within the subnet, cabinet, closet, building, etc? Or is the cluster on a vlan that spans multiple subnets, locations, etc?

    Jason...AKA CirqueDeSQLeil
    _______________________________________________
    I have given a name to my pain...MCM SQL Server, MVP
    SQL RNNR
    Posting Performance Based Questions - Gail Shaw[/url]
    Learn Extended Events

  • When you stop the SQL Server service the service account will be logged off the domain. When you try to start the SQL Server service again, whether on the active or the (ex-)passive node it will need to log on again. If it can't authenticate with the domain then that authentication will fail, so SQL Server won't be able to start.

    If you stop the SQL Server service through Cluster Administrator or using cluadmin.exe then Cluster Services knows that it's meant to be down and so won't attempt a failover to the passive node.

    If you stop the service through the Services applet or using sqlservr.exe then the service stop happens outside of Cluster Services ken so Cluster Services will try to bring it back up again (the exact profile regarding the number of attempts before it does a failover depends on the cluster configuration).

    If you don't stop the SQL Server service before disconnecting the network then SQL Server will continue to operate until it tries to do something that requires communication with the domain and/or network resources. What happens in such a case depends on what it is trying to do: it will result in an error message being logged in the SQL Server and Windows logs, but some things may cause more significant impacts, perhaps even crashing the service.

  • Mani-584606 (11/30/2009)


    Here, when the entire network goes down, will the SQL Services from active node try to move to passive node? or will they stay at active node itself as the entire network is gone. I do not want to move the SQL Servcies from active node to passive node.

    Provided the cluster heartbeat is on a separate network (if not, then go fix that ASAP), then the loss of the primary network will not result in instance failover.

    -Eddie

    Eddie Wuerch
    MCM: SQL

  • Windows Clustering is NOT network aware, except for the Heartbeat between the servers. If the network were to go down and the private heartbeat network is still up, Windows will not fail the cluster.

    You can manually fail over the cluster in this case provided your cluster spans multiple networks segments and the other segments are not affected.

    Raymond Laubert
    Exceptional DBA of 2009 Finalist
    MCT, MCDBA, MCITP:SQL 2005 Admin,
    MCSE, OCP:10g

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