I have question about iostat (hardisk detect)

Posted on 2011-10-21
Last Modified: 2012-06-22
Why parameters are different between iostat 1 -x and iostat -x

And it seem  iostat 1 -x  is more exact?

Question by:redstar01
    LVL 68

    Expert Comment

    1 is the interval in seconds.

    The first block of iostat  provides statistics concerning the time since the system was booted.

    Without an interval parameter iostat will terminate after diplaying this.

    When supplying an interval parameter each subsequent report covers the time since the previous report.


    Author Comment

    I know that '1' is seconds update

    But when overload, iostat 1 -x allway show %ubtile = 100 -> its exact
    while iostat -x never show 100%util, only <50-60%, show it's not exact!

    Because I want to get loadding of each harddisk (with programming script to get each disk)
    And I wonder if there is any way to know exact %util

    And really that   iostat -x   and  iostat 1 -x  is seem conflict?

    LVL 68

    Expert Comment

    >> And really that   iostat -x   and  iostat 1 -x  is seem conflict? <<

    It's just another base - accumulated since reboot or in last interval.

    Author Comment

    but "-x" , parameters seem not exact, allway show <50%util if hdd really overload
    while "1 -x" show parameters greater much, and 100%util if hdd  really overload

    Author Comment

    My target:
    I need know one HDD is overload or Not any time!
    LVL 68

    Accepted Solution

    I can only repeat a last time:

    -x alone shows the values since reboot. It seems that your disk (presently overloaded or not) has been poorly utilized for a long time period between reboot and now, so that despite of it being presently overloaded the accumulated value shows < 50 %.


    You rebooted at 00:00.
    It is now 12:00 the same day.

    The disk in question has been utilized 0% from 00:00 to 06:00
    It has been utilized 100% from 06:00 till now (12:00).

    iostat -x will show 50%, iostat -x 1 will show 100%.



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