Physical Disk Performance Measurement

  • hemant.chaurasia-942319

    SSC Journeyman

    Points: 90


    We have a typical RAID 10 (2+2) configuration with 4 HDD on one of our production database server where I observed in perfmon for the drive which is configured with RAID 10 configuration.

    Avg. Disk Read Queue Length - 12.51

    Avg. Disk Write Queue Length - 0.06

    Somewhere I read , I should divide these figures with the no of spindles. Now the question is , should I divide these values by 4 or 2 and what should I interprete from these values ?



  • Toby Harman

    SSCarpal Tunnel

    Points: 4128

    I would suggest the answer is two..

    Either you have mirrored two spindles two times and then striped the resulting array (RAID 1+0) is which case everything that happens to one spindle MUST happen to the other synchronously or you have striped two spindles two times and then mirrored the results (RAID 0+1), in which case a single write will also have to be written to two physical spindles.

    BTW - doing the mirror 1st and then the stripe actually increases your reliability once you get to 6 spindles.

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