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Disk in Read 29M% of the time - What the heck?!

Proposed Disk in Read 29M% of the time - What the heck?!

  • Friday, March 09, 2012 1:15 AM
     
     
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    After running the MAP Toolkit for two weeks, I've been examining the results with satisfaction.  However, I'm not getting total Read IOPS vs. Write IOPS, so I looked at:

    Inventory and Assessment -> Data Collection -> Performance Metrics Results

    I looked at the individual machines' physical disks to get total % of time in read vs. write, then used that as the ratio of read IOPS to write IOPS.  That worked fine except for one machine which showed that the % Disk Read time is 29,000,000!  Attaching a snapshot here.

    This is a physical machine with two LUNs presented by an array.  RAID 1 for number 1, and RAID 10 for number 2.  Any ideas on how to analyze this wackiness?  

     

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  • Monday, March 12, 2012 6:15 PM
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    I've looked into this and I can't tell why this is happening without seeing the raw performance data. It might be related to the SAN, but I'm not sure.  If you are willing to send us the database, send an email to mapfdbk@microsoft.com and reference this post. I can then set up a secure file transfer site. Thanks.

    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

     
  • Monday, March 12, 2012 6:19 PM
     
     
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    It's all local storage, no SAN involved.
     
  • Wednesday, March 14, 2012 5:54 PM
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    I received your email and replied, but I have not heard back. Let me know if you still need assistance, thanks.

    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

     
  • Friday, March 23, 2012 8:49 PM
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    It looks like the raw data MAP is getting from the machine is giving us those strange numbers. I would guess this is a RAID controller/driver issue. You should be able to confirm this by opening PerfMon and adding these counters:

    Make sure you select the disk you want to see in the “Instances of selected object:” section. After clicking ok, delete the ‘% Processor Time’ counter and then select one of the counters you added. You should see strange numbers that are over 100%. I wouldn’t pay much attention to the graph part, it can scale in strange ways.

    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.