SQL Server Performance

%Disk Time shows value more than 100

Discussion in 'General DBA Questions' started by ramkumar.mu, Jul 7, 2006.

  1. ramkumar.mu New Member

    The counter Physical Disk: %Disk Time shows values as given below

    AverageMinimumMaximum
    -----------------------
    603 0 4657

    where as the description in performance monitor says "% Disk Time is the percentage of elapsed time that the selected disk drive was busy servicing read or write requests."

    can you please tell me where i am going wrong...

    Thanks,
    Ram

    "It is easy to write code for a spec and walk in water, provided, both are freezed..."
  2. ramkumar.mu New Member

    its quite urgent! can anybody gimme a clue to this ASAP

    Thanks,
    Ram

    "It is easy to write code for a spec and walk in water, provided, both are freezed..."
  3. dineshasanka Moderator

    As a rule of thumb, the % Disk Time counter should run less than 55%.If this counter exceeds 55% for continuous periods (over 10 minutes or so during your 24 hour monitoring period), then your SQL Server may be experiencing an I/O bottleneck.

    Look into the ways to increase the I/O performance on the server, or to reduce the on the server. Some ways to boost disk I/O include adding drives to an array (if you can), getting faster drives, adding cache memory to the controller card (if you can), using a different version of RAID, or getting a faster controller.

    ----------------------------------------
    http://dineshasanka.blogspot.com/
  4. ramkumar.mu New Member

    I get your point Dinesh. But can a '% value' go above 100 like (603 and 4657) i said above?

    Thanks,
    Ram

    "It is easy to write code for a spec and walk in water, provided, both are freezed..."
  5. dineshasanka Moderator

  6. ramkumar.mu New Member

    oh! That involves some more calculations to be done. Thanks Dinesh.

    Thanks,
    Ram

    "It is easy to write code for a spec and walk in water, provided, both are freezed..."
  7. joechang New Member

    ignore this counter, it has no meaning in server systems,
    stick to the counters i listed in the qdpma section
  8. satya Moderator

    I would go with Joe's suggestion in this regard as it has proven from his experience about finding the root cause.

    Satya SKJ
    Microsoft SQL Server MVP
    Contributing Editor & Forums Moderator
    http://www.SQL-Server-Performance.Com
    This posting is provided �AS IS� with no rights for the sake of knowledge sharing.
  9. ramkumar.mu New Member

    Can you please post the link? I couldnt figure out the exact location.

    Thanks,
    Ram

    "It is easy to write code for a spec and walk in water, provided, both are freezed..."
  10. ghemant Moderator

    Hi,
    Referhttp://www.qdpma.com/

    Regards

    Hemantgiri S. Goswami
    ghemant@gmail.com
    "Humans don't have Caliber to PASS TIME , Time it self Pass or Fail Humans" - by Hemantgiri S. Goswami
  11. ramkumar.mu New Member

    Do we have any benchmark values for the following counters???


    Processor% Processor Time
    % Privileged Time
    Interrupts/sec
    System Context Switches/sec
    Memory Pages/sec
    Pool Nonpaged Bytes
    Pool Paged Bytes
    Process % Processor Time
    Private Bytes
    Virtual Bytes
    Physical Disk Avg. Disk Read Queue Length
    Avg. Disk sec/Read
    Avg. Disk sec/Write
    Avg. Disk Write Queue Length
    Disk Read Bytes/sec
    Disk Reads/sec
    Disk Write Bytes/sec
    Disk Writes/sec




    Thanks,
    Ram

    "It is easy to write code for a spec and walk in water, provided, both are freezed..."
  12. satya Moderator

    YOu have define the benchmark as per your environment, as it differs from installation to installation.

    So capture the counters during the busy period and less traffic hours, that will give you more information on how the system is using the resources.

    Satya SKJ
    Microsoft SQL Server MVP
    Contributing Editor & Forums Moderator
    http://www.SQL-Server-Performance.Com
    This posting is provided �AS IS� with no rights for the sake of knowledge sharing.
  13. joechang New Member

    you should trying reading the explanations i gave with the counters to understand what they mean

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