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Duplexing the transaction log

  • February 1, 2010 at 6:30 am

    #216227

    Hi

    an Oracle DBA asked me if SQL has some technique to safeguard the transaction log from disk failures. Oracle uses duplexing. I don't think this exists for SQL but maybe I'm wrong?

    Thierry

  • February 1, 2010 at 6:32 am

    #1111557

    The SQL transaction log is a sequential write log so no duplexing.

    Best way to protect it is to back it up frequently and store on a raided drive to give the protection at the disk level

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  • February 1, 2010 at 6:37 am

    #1111561

    Hi George

    thanks for the prompt reply. What Oracle actually does is writing the same info to 3 different files (preferrably of course on different drives) so when one file is lost it can continue because there's still 2 exact copies of it.

    So I know SQL doesn't do this but I thought maybe someone has heard of a 3rd party tool that mimics this behaviour?

    Regards

    Thierry

  • February 1, 2010 at 6:42 am

    #1111563

    Thierry,

    Like George said, RAID is essentially will have the same effect. Only difference it is not managed by SQL Server.

    Also, duplexing is just an extension of mirroring. There is a lot of articles on how to setup RAID.

  • February 1, 2010 at 6:44 am

    #1111565

    personally I am not aware of such a tool and it sounds too removed from how SQL works for there to be one.

    Various HA methods can give extra protection (log shipping, database mirroring, replication, even disk replication)

    Perhaps SQL files don't get corrupted as often as Oracle ones 🙂

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  • February 1, 2010 at 6:44 am

    #1111566

    Check this link that explains duplexing and RAID very well I thought.

    Duplexing and RAID

  • February 1, 2010 at 6:56 am

    #1111579

    thx guys,

    these are the answers I expected (also the one about Oracle having more corruption issues than SQL :-D)

    We're already using raid protection, frequent trn log backups, etc. so we're pretty safe I might say.

    I just needed some confirmation on the duplexing because the guy who asked me is my boss (and an Oracle expert I must add :))

    Thx again

    Thierry

  • February 1, 2010 at 7:01 am

    #1111585

    Glad we were able to help you.

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