Performance of principal db in Mirroring

  • Hi

    According to http://technet.microsoft.com/en-US/library/cc917680 in database mirroring,"As the principal server hardens its principal database log records to disk, it also sends them to the mirror. The principal then waits for a response from the mirror server. The mirror responds when it has hardened those same log records to the mirror's log disk."

    I want to know if this behavior causes problem in performance of principal database because of these waits?

  • It can, yes.

    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
  • and we can decrease the time for waiting with :

    ALTER DATABASE dbname SET PARTNER TIMEOUT 20 ?

  • No, that would just increase the delay before a mirroring failover.

    To reduce the impact of mirroring, reduce the latency of the hardening of the mirror's log records, that's the line's latency and the write latency on the mirror's log drive.

    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

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