• jheim (9/4/2012)


    Good article. Covered the basic configurations that people are "thinking about". Thanks.

    Please do not forget to rate the article if you found it useful

    jheim (9/4/2012)


    To keep the nodes consistent...is it simply relying on mirror like transaction shipping from DB to DB? Are there issues with speed if non-shared disk instances are far away?

    It uses mirroring endpoints to communicate between the replicas and operates in the traditional mirroring synch or asynch modes. It's basically mirroring on steroids.

    The non shared disks are irrelevant to an extent its the comms between the replicas (sql instances) that are important, same with mirroring.

    jheim (9/4/2012)


    Secondly, it sounds like the replicas with separate disk have to be read-only at best....like mirroring? is that true?

    Yes they're standby or read only

    jheim (9/4/2012)


    Also, the AO is described as a collection of DBs, not instances....or do I have that wrong?

    An AlwaysOn group is a collection of databases that are replicated out to a set of defined partners\replicas.

    jheim (9/4/2012)


    That would make it on a par with mirroring.....mirroring doesn't deal with the system DBs and all they contain (authentication, sql agent stuff, etc.. etc...). Does AO deal with replicating system DBs to instances using separate disks?

    System databases are not replicated, check Books Online there are a whole host or pre reqs and restrictions around AlwaysOn.

    jheim (9/4/2012)


    My biggest desire is to have something that looks like a cluster (with all its failover wonderfulness) across a long distance with separate disk. I don't mean something that does it halfway like mirroring on a database level....I want the whole instance to be replicated including system dbs. I don't want to script off pieces of the sql server instance and restore them to really get the failover up to speed....like logins and agent jobs and other stuff that changes over time.

    I dont need the failover to be updatable....just to be "complete".

    P.S. I have read about partial isolation for DB users and its only a halfway fix for that particular issue.

    comments please, thanks.

    At present contained databases are possible but there are still limitations, again check Books Online for the pre reqs and restrictions

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