> After having the Apps team upgrade Tivoli to FixPack6, We've had
> occasions where some of our servers reach "HighCPUWaitTime" wait
> figures over 20.. This kicks off Tivoli's warning alerts (which i
> usually take with a pinch of salt), anything over 10 -which is the
> default as we never saw these messages prior to FP4..
iowait in a vacuum doesn't mean much. Other things besides I/O can
affect it. A well-running system may have a large I/O figure and a poor
one can have zero.
Quote:> In the IBM infodoc, it associates HighCPUWaitTime with High I/O, which
> I understand but don't really know what an idea figure should be.
There is no ideal figure. Potentially, you could examine a system under
normal circumstances and use a rise in that figure as an indication that
something changed, but you won't know if that change was good or bad in
Systems where you have few CPU jobs, lots of available CPU, and the CPU
is faster than the I/O will usually show iowait. Where all those
situations are normal (think a beefy database), then having a raised
iowait would also be normal.
Quote:> Anyhow, what I would like to know is at what point would you start
> getting concerned with a servers performance CPUWait vs IO wait?
When it's abnormal for what that machine does. If my CPU-intensive
renderfarm ever showed i/o wait, I'd be concerned. If my database
server showed it, I wouldn't be.
Quote:> I,e, can I change the threshold from 10 (default) to something like 30?
Senior Technical Consultant TAOS http://www.taos.com/
Got some Dr Pepper? San Francisco, CA bay area
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