What is I/O Wait

[Sagar Sirdesai]

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

Sagar

[Wim Rombauts]

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.

[Ricky_HK]

idle + iowait = total idle time

[muruganantham raju]

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

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

e.g.

# 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

Regards,
Muru

[Hakki Aydin Ucar]

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

related with Disks that was busy with another process before..

[Hakki Aydin Ucar · Accepted solution]

Also check these out:

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=62143

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1086719

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=138987

http://h21007.www2.hp.com/portal/download/files/unprot/devresource/Docs/TechPapers/UXPerfCookBook.pdf

[Sagar Sirdesai]

Thanks to all for their replies