Best procedure to introduce clustering in a high OLTP environment

  • We have a high OLTP environment. What's the best procedure to follow for minimum down time.

  • Could you provide more information?

    Are you able to re-point the applications etc?

    If you are I would personally build a new cluster then mirror the databases to the new cluster and when you are ready failover the mirroring.

    There are many other options available though, again it all depends on how your app is architected and how much control over it you have.

    Cheers

    Mat

  • Are you able to re-point the applications etc? YES

    I will try to work on the mirroring option.

    Can I know more about other options?

  • deep_kkumar (5/22/2012)


    Are you able to re-point the applications etc? YES

    I will try to work on the mirroring option.

    Can I know more about other options?

    you could also log ship the databases and when in sync make the switch, alternatively if they're small databases just detach, copy and re attach them.

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    "Ya can't make an omelette without breaking just a few eggs" 😉

  • Perry Whittle (5/22/2012)


    deep_kkumar (5/22/2012)


    Are you able to re-point the applications etc? YES

    I will try to work on the mirroring option.

    Can I know more about other options?

    you could also log ship the databases and when in sync make the switch, alternatively if they're small databases just detach, copy and re attach them.

    This is what I would do. I'd opt for backup restore over detach though for an easier rollback (IMO).

    If possible, I'd consider setting up a DNS alias and do a staged migration from host name to the alias. This could be done in advance of the migration and when you're done, change DNS to point at the new cluster.

  • I've never found a detached database difficult to re attach, unless of course some clown moves the files instead of copying them.

    Even with backup and restore you want the original database offlined to stop access and you have to wait for the backup\restore ops to complete as well as the file copy op.

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    "Ya can't make an omelette without breaking just a few eggs" 😉

  • Perry Whittle (5/26/2012)


    I've never found a detached database difficult to re attach, unless of course some clown moves the files instead of copying them.

    True. Its just my preference. Using a back up just seems cleaner and safer to me. It means less network traffic when compressed. Theres a risk of accidentally deleting or loosing the files when in a detached state.

    Pro's and cons.

    Perry Whittle (5/26/2012)


    Even with backup and restore you want the original database offlined to stop access

    Always do.

  • MysteryJimbo (5/26/2012)


    Theres a risk of accidentally deleting or loosing the files when in a detached state.

    Take a database offline and then try to delete, move or rename one of its files, then try to online it again 😉

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    "Ya can't make an omelette without breaking just a few eggs" 😉

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