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Performance Counters which one

  • July 13, 2009 at 10:08 am

    #202243

    http://blogs.technet.com/jonathanalmquist/archive/2009/04/06/how-can-i-gauge-operations-manager-database-performance.aspx

    In the above it says (Avg. Disk Reads/sec) + (Avg. Disk Writes/sec)

    I thought these two were how long in seconds is the disk taken.

    I see AVG DISK SEC / READ which is how long in seconds disk take..

    but not the AVG DISK READ/SEC counter

    I have DISK READ SEC but not AVG DISK READ SEC

    Physical counters on Permon.

    Which one?

  • July 13, 2009 at 12:39 pm

    #1024093

    Avg. Disk Sec/Read and Avg. Disk Sec/Write are the values you're looking for.

    However, to see how your disk is performing, it's usually more useful to look at % Disk Time and Avg. Disk Queue Length. The first one is pretty obvious, it shows how busy you're I/O. The second shows how many processes are having to wait to access the disk, reads or writes.

    ----------------------------------------------------The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood... Theodore RooseveltThe Scary DBAAuthor of: SQL Server 2017 Query Performance Tuning, 5th Edition and SQL Server Execution Plans, 3rd EditionProduct Evangelist for Red Gate Software

  • July 13, 2009 at 9:03 pm

    #1024220

    Thanks but i want the IOPS as we only got 420 IOPS and i want to be sure we not reaching these limits.

    Cheers

  • July 14, 2009 at 9:42 am

    #1024514

    Hi Tracy,

    The IOPS counter you are looking for is Physical Disk:Disk Transfers/sec

    Regards,

    Craig

  • July 14, 2009 at 12:08 pm

    #1024608

    i will look at that counter too.

    Is doing the following with the two counters Physical Disk Reads / Sec and Physical Disk Writes/Sec

    Then i have all disks information and performing these calucations

    Raid 0 -- I/Os per disk = (reads + writes) / number of disks

    Raid 1 -- I/Os per disk = [reads + (2 * writes)] / 2

    Raid 5 -- I/Os per disk = [reads + (4 * writes)] / number of disks

    Raid 10 -- I/Os per disk = [reads + (2 * writes)] / number of disks

    (You can use the above RAID calculations to determine the I/Os per disk. 120 reads + (4 * 150 writes) / 4 physical disks = 180 I/Os per disk. This is over the general rule of 125 I/Os per disk capacity. This system has a disk bottleneck.

    Not good from my results if above is valid

    disk read reads write disks raid using above calc san iop maximum

    194.28 498.12 Temp DB 2 1 595.26 160

    308 425.07 Temp DB 2 1 579.07 160

    294.51 384.86 Temp DB 2 1 532.12 160

    552.12 249.49 Temp DB 2 1 525.55 160

    DISK TRANSFER / SEC

    118.384166191947

    3.86856420768792

    269.378040336257

    (This is 269 IOPS Sec ?)

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