Database Mirroring or Replication

  • Hi all, just looking for some advice.

    I've got two servers a good few mile apart with a latency of @40msec.

    I want both resilient and availability, but not sure of the best option.

    Will database mirroring with witness (Standard edition SQL) be ok with the latency?

    or would a merge replication be a better option? (last used was @5years ago and required a lot of effort to maintain it)

    Thanks

    Shiraz

  • If you want both databases to be available you can not choose mirroring anyway. For distance you can pick mirroring but i would not set it up for high safety.

  • As said before, if you need both databases available replication is the only option.

    Merge replication is only necessary if you want to make changes on both databases, otherwise I would suggest using transactional replication.

    In case only one instance of the DB's needs to be accessible at a time, I would go for mirroring. The main reason for that is that replication makes it a lot more difficult if you need to change the database schema. Also when you use replication the distributor must be a full SQL Server instance, while you can use SQL Express as a witness server.

    The latency and/or distance shouldn't be a problem in either case, but when you choose synchronous mirroring (Full safety) it will have a performance impact. As long as your transactions are short it shouldn't be too bad.

    [font="Verdana"]Markus Bohse[/font]

  • Thanks for your advice, The main reason I am looking at these two options is for automatic failover.

    Mirroring with a witness server does this, however I am restricted to the standard edition which means safty on.

    The merge replication also achieves the same as both databses are available all the time and if the user conection strings are coded to conect to one first then try the other, however if both database are available, then users will be conecting to whichever server is nearest.

    My preference is mirroring, due to the fact its easier to setup and manage, however I think I need to carry out tests to confirm how much effect the latecy has on the end user.

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