v$filestat & write & read averages
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Thread: v$filestat & write & read averages

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  1. #1
    Join Date
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    Orlando, FL
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    Post

    I am trying to figure out the average write time by datafile using the v$filestat view. The problem is I can't seem to
    ever get the WRITETIM or READTIM to display anything but 0.
    Yes, I do have TIMED_STATISTICS set to TRUE

    Has anyone else seen this problem with 8.1.5?
    Would anyone have any other suggestions on how to calculate
    the average write & read times?
    Vinnie Salerno

  2. #2
    Join Date
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    Saskatoon, SK, Canada
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    That could also mean that your latency is 0. If you are on unix, then you could use the


    iostat -ncxtM 3

    view the disk latencies.

    Sam
    Thanx
    Sam



    Life is a journey, not a destination!


  3. #3
    Join Date
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    Run the following as sys:

    col name for A40
    select d.name, a.phyrds, a.phywrts, a.avgiotim
    from v$datafile d, v$filestat a
    where a.file# = d.file#;

  4. #4
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    I ran the previous script & AVGIO is still 0.
    Vinnie Salerno

  5. #5
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    If I run iostat I get the following:

    extended device statistics
    r/s w/s Mr/s Mw/s wait actv wsvc_t asvc_t %w %b device
    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t0d0
    1.0 158.7 0.0 1.2 0.0 1.0 0.0 6.2 0 97 c0t1d0
    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t6d0
    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 prime5:vold(pid246)

    Shows c0i1d0 is busy writing, yet v$FILESTAT.WRITTIM is still 0. How can that be?
    Vinnie Salerno

  6. #6
    Join Date
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    Originally posted by salernov
    I ran the previous script & AVGIO is still 0.
    There are currently three open bugs on READTIM being wrong in v$filestat. Bugs 1107600, 1162763, and 1391738.

    Which version of Oracle R U using?


  7. #7
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    8.1.5. Is there a patch?
    Vinnie Salerno

  8. #8
    Join Date
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    Originally posted by salernov
    8.1.5. Is there a patch?
    I don't know. I use 8.1.7.


  9. #9
    Join Date
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    If it had not yet been fixed on the 8.1.7 then sure you can expect it to be there on 8.1.5 ;D when the avsc_t goes beyond 20 then you would want to worry too much. Untill then can relax .

    Sam
    Thanx
    Sam



    Life is a journey, not a destination!


  10. #10
    Join Date
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    Location
    Orlando, FL
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    I got it working. I had to actually set timed_statistics =true
    in my init file. The alter session did not work.

    If I am using this to calulate my DISK I/O, what is the time scale used by ORACLE in the READTIM & WRITETIM?

    I am looking for the # of writes/sec across my mount points.

    Vinnie Salerno

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