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SQL 2014 AlwaysOn vs AlwaysOn+FCI

  • July 22, 2015 at 5:41 am

    #302609

    I've worked with clusters (active/active, active/passive) and AlwaysOn. I've read about using AlwaysOn + FCI, but am not quite grasping what adding FCI provides me with AlwaysOn. With AlwaysOn, I take shared data out of the picture and it provides me fault tolerance and automatic failover to one other node, while also providing read-only access with backups to the secondary nodes.

    I've been doing this for many years and just for some reason need some clarification on adding FCI to AlwaysOn.

    Thanks

  • July 22, 2015 at 5:45 am

    #1814071

    Terminology first. AlwaysOn is a marketing term, not a feature.

    The features are:

    Always On Availability Groups

    Always On Failover Clustering

    Always On Availability groups are the feature which replaces mirroring, the multiple servers with local storage, etc.

    Always On Failover Clustering is the old clustering that's been available since SQL 7 or so, multiple nodes with shared storage and node failovers

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

  • July 22, 2015 at 7:00 am

    #1814090

    ItsDaveTime (7/22/2015)

    I've worked with clusters (active/active, active/passive) and AlwaysOn. I've read about using AlwaysOn + FCI, but am not quite grasping what adding FCI provides me with AlwaysOn.

    With AlwaysOn, I take shared data out of the picture and it provides me fault tolerance and automatic failover to one other node, while also providing read-only access with backups to the secondary nodes.

    An FCI is providing instance level redundancy rather than AO groups database level redundancy.

    Think of this, on your primary site you may have an instance of sql server that doesn't just have your primary AO group databases, but may have other critical app databases too, an FCI could be used to provide primary site redundancy for all the primary site databases, whilst still participating in an AO group

    ItsDaveTime (7/22/2015)

    I've been doing this for many years and just for some reason need some clarification on adding FCI to AlwaysOn.

    Thanks

    See my articles at the following links for detail on combining FCIs with AO groups

    http://qa.sqlservercentral.com/articles/Failover+Clustered+Instance+(FCI)/92196/[/url]

    http://qa.sqlservercentral.com/articles/High+Availability/109978/[/url]

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