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
Peace, Shorty
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