SQL Server Performance

Missing performance monitor data

Discussion in 'Performance Tuning for DBAs' started by greenant, Nov 12, 2008.

  1. greenant New Member

    I'm using performance monitor to help diagnose performance problems on several different servers. I've created a counter log that captures samples every 60 seconds and let it run for a few days to get a good picture of how the servers perform. When I looked at the log file, I found that for many of the samples (70% +), no data was captured for the following counters:
    Avg. Disk Queue Length
    Avg. Disk Read Queue Length
    Avg. Disk Write Queue Length
    Avg. Disk sec/Read
    Avg. Disk sec/Write
    Avg. Disk sec/Transfer
    For all of the other physical disk counters and other counters the data was captured for all samples. The missing data does not appear to be related to the load on the server.
    Does anyone know why the performance data data would be missing for the disk latency and queue counters? Is this a problem with the installation/configuration of the performance counters?
  2. satya Moderator

    No data captured means there is no values against these counters?
    What is the service pack level of Operating system on this server?
    Can you get the values when executing real time than as a scheduled job from SYSMON tool?
  3. greenant New Member

    One server is Windows Server 2003 Enterprise R2 Standard Edition SP 1. The other is Windows Server 2003 Standard x64 Edition SP1.
    I can get values when executing real time but I see a similar issue. There are no values or large gaps in the disk latency (avg. disk sec/read etc.) but the queue length looks mostly ok. I used the Disk tranfers/sec to verify that there is disk activity and the load doesn't seem too high 150 - 200 IOPS at around 1MBPS. Sometime it spikes up to over 1000 IOPS and 14MBPS for very short periods.
    When I am able to get queue length data it is very high, average is over 300.
    Do you think that it is the load on the disk that is causing the counters to get dropped or do you think that it's a problem with the disk performance counters?
    Have you had a similar issue?
    The server is using an HP Smart Array P400 with 6 SAS drives configured in 3 RAID 10 arrays. Do you know if there is any way to show the disk queueing and latency using any HP tools rather than perfmon?

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