[collectd] question about new "disk" metrics

[Gerardo Herzig]

Great! Im testing it right now. Yes, it will be nice to see the maths involved in the 'utilization %' calculations.

Thanks!

Gerardo

----- Mensaje original -----
> De: "Marek Becka" <marek.becka at superhosting.cz>
> Para: collectd at verplant.org
> Enviados: Viernes, 3 de Julio 2015 11:52:47
> Asunto: Re: [collectd] question about new "disk" metrics
> 
> On 06/16/2015 11:12 AM, Markus "Shorty" Uckelmann wrote:
> > Am 16.06.2015 um 06:32 schrieb Markus "Shorty" Uckelmann:
> >> Am 16.06.2015 um 00:20 schrieb Gerardo Herzig:
> >>> Hi all. Im trying to use the "disk" metrics of the new 5.5
> >>> colletcd version, in order to avoid the "iostat" ruby wraper.
> >>> What is cool about "iostat -x" is the "disk util%", to knowing
> >>> how stressed the disk are.
> >>
> >>> So, it is not clear to me what maths are involved in that
> >>> calculations. Anyone knows if it is possible now with the new
> >>> disk-plugin metrics?
> >>
> >> Under Linux it should (sorry, haven't checked the code) derive
> >> from
> >> the iostats utility. From the man page:
> >>
> >> %util Percentage  of  elapsed time during which I/O requests were
> >> issued to the device (bandwidth utilization for the device).
> >> Device
> >> saturation occurs when this value is close to 100% for devices
> >> serving requests serially.  But for devices serving requests in
> >> parallel, such as RAID arrays and modern SSDs, this number does
> >> not
> >> reflect their performance limits.
> >
> > Mea culpa! I just didn't read your post correctly. I can't answer
> > your
> > questions.
> >
> > So far I was able to find the "weighted_time" variable in the code
> > of
> > disk.c. This should be the last field from /proc/diskstats which
> > contains the utilization as described above. But I'm not sure what
> > happens to this metric (my C is bad). Because it doesn't show up in
> > the output of the plugin.
> >
> > So someone with knowledge of that plugin might jump in. I would be
> > interested in the disk utilisation too ;)
> >
> > BTW: Some interesting links I found:
> >
> > http://www.mjmwired.net/kernel/Documentation/iostats.txt
> > http://www.xaprb.com/blog/2010/01/09/how-linux-iostat-computes-its-results/
> >
> > https://stackoverflow.com/questions/4458183/how-the-util-of-iostat-is-computed
> >
> >
> >
> 
> Hi, I'm using own patch for disk plugin that adds disk utilization
> and
> number of in-flight requests.  I didn't request pull to the upstream
> yet. The patch can be found at
> https://github.com/marekbecka/collectd/pull/1
> 
> 
> 
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