[CentOS] Correlate i/o with a process

Sat Aug 18 17:51:19 UTC 2007
Dag Wieers <dag at wieers.com>

On Fri, 17 Aug 2007, Mag Gam wrote:

> On 8/17/07, John R Pierce <pierce at hogranch.com> wrote:
> > Mag Gam wrote:
> >
> > > I have a server with 2 HBAs, and the users keeps complaining about
> > > performance problems. My question is, how can I relate the process
> > > with high I/O wait? Also, is it possible to see how much data is being
> > > pushed thru by my 2 HBAs?
> >
> > iostat (part of the sysstat package) will answer your 2nd question.
> >
> > I dunno how to measure io wait time per process.  maybe IBM's NMON can
> > do that, not sure, I haven't used it for a while.
> > http://www-941.haw.ibm.com/collaboration/wiki/display/WikiPtype/nmon
>
> Thanks John.
> 
> Yes, this is a tricky question, but I face this a lot....Unfortunately, I am
> not sure how to check the adapter throughput, and what process is causing
> the i/o wait.

I believe that recent kernels have a patch applied that show io counters 
per process. I haven't looked into it yet though.

This is one of the most important items on my wishlist for dstat, a topio 
plugin next to the existing topcpu and topmem plugins.

Kind regards,
--   dag wieers,  dag at wieers.com,  http://dag.wieers.com/   --
[Any errors in spelling, tact or fact are transmission errors]