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What is I/O Wait

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Sagar Sirdesai
Trusted Contributor

What is I/O Wait

Hi All,
I need whether I/O Wait is a Measure of CPU Utilization or Idle Time.

Wim Rombauts
Honored Contributor

Re: What is I/O Wait

I/O Wait is the time the CPU is doing nothing because all processes it could work on are waiting for I/O operatons to complete.

So, there is no CPU utilization, but it's not idle time either.
Frequent Advisor

Re: What is I/O Wait

idle + iowait = total idle time
muruganantham raju
Valued Contributor

Re: What is I/O Wait

Hi Sagar,
I/O wait is accounted for idle time.

To find out CPU IDLE % in your system, run the sar command.


# sar -u 1 2

HP-UX biavm4-3 B.11.23 U ia64 08/18/10

04:47:47 %usr %sys %wio %idle
04:47:48 0 0 0 100
04:47:49 0 0 0 100

Total Idle% = %wio + %idle

Hakki Aydin Ucar
Honored Contributor

Re: What is I/O Wait

%wio - idle with some process waiting for I/O ;

related with Disks that was busy with another process before..
Sagar Sirdesai
Trusted Contributor

Re: What is I/O Wait

Thanks to all for their replies