[rrd-users] basic rrdtool usage - short intervals
spork at bway.net
Sat Sep 18 02:48:35 CEST 2010
I'm having some trouble with some very basic rrdtool setups. I'm doing various
benchmarking tasks and I want to sample some basic info while my benchmarks are
running (load, disk tps, disk i/o, etc.). I've got no problem collecting the
data nor feeding it into rrdtool, but I think I'm missing something regarding
the timing of pumping data into the db. I'm trying to do very quick samples -
once every 5 seconds or less so I can really see what's happening during the
relatively short run of my benchmark.
What I'm finding when I dump the rrd is that there are a ton of empty values
and the stepping is 3 minutes rather than the 15S I specified when I created
The create command:
rrdtool create arcsize.rrd --start N --step 15 DS:arcsize:GAUGE:600:0:5000
RRA:MIN:0.5:12:3660 RRA:MAX:0.5:12:3660 RRA:AVERAGE:0.5:12:3660
The update for this one in my script looks like this:
rrdtool update arcsize.rrd "N:$arcsize"
I have verified it's spitting out values; I print to STDOUT while it runs as
well. I run the script in a "while true" loop with a 14S sleep. I've also
tried manually updating with the same value, etc. with the same result that the
steps in the dump of the rrd don't seem to match up.
I mostly used this guide to try and figure things out:
What am I missing? I'm really hoping to get a basic working knowledge of
rrdtool as I've been doing more and more stuff where it would be nice to graph
arbitrary system stats at a high sample rate over a short period of time - this
would certainly make the data easier to digest.
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