RRD performance problems (updated)

Noting: - rrd 1.3.late has MMAP based io, doubling update speeds - our munin-cgi-graph script is getting pretty nifty, maybe we can switch to on-demand graphing?

RRDtool 1.4 includes rrdcached, which does exactly this: <http://oss.oetiker.ch/rrdtool-trac/wiki/RRDtool14>. probably more sensible than rolling our own. less work, too :-)

I'm pushing this one to "later", since it would require extensive work.

Since the main performance contender is the graphing subsystem, the 1.5 will provide a greater on-demand graphing experience and therefore should improve the performance issue.

Before we do this we should consolidate plugin time series to single rrd files. This has better graph performance, and probably also update performance. Jimmy writes:

# one datasource per rrdfile
for i in $(seq -w 1 1000); do rrdtool create single-$i.rrd DS:42:GAUGE:600:U:U RRA:AVERAGE:0.5:1:576 RRA:MIN:0.5:1:576 RRA:MAX:0.5:1:576 RRA:AVERAGE:0.5:6:432 RRA:MIN:0.5:6:432 RRA:MAX:0.5:6:432 RRA:AVERAGE:0.5:24:540 RRA:MIN:0.5:24:540 RRA:MAX:0.5:24:540 RRA:AVERAGE:0.5:288:450 RRA:MIN:0.5:288:450 RRA:MAX:0.5:288:450; done

time for i in $(seq -w 1 1000); do rrdtool update single-$i.rrd N:9492432; done
real    0m10.918s
user    0m4.604s
sys     0m6.440s

# 10 datasources per rrdfile
for i in $(seq -w 1 100); do rrdtool create multi-$i.rrd $(for j in $(seq -w 1 10); do echo -n "DS:$j:GAUGE:600:U:U "; done)  RRA:AVERAGE:0.5:1:576 RRA:MIN:0.5:1:576 RRA:MAX:0.5:1:576 RRA:AVERAGE:0.5:6:432 RRA:MIN:0.5:6:432 RRA:MAX:0.5:6:432 RRA:AVERAGE:0.5:24:540 RRA:MIN:0.5:24:540 RRA:MAX:0.5:24:540 RRA:AVERAGE:0.5:288:450 RRA:MIN:0.5:288:450 RRA:MAX:0.5:288:450; done

time for i in $(seq -w 1 100); do rrdtool update multi-$i.rrd N:9492432:9492432:9492432:9492432:9492432:9492432:9492432:9492432:9492432:9492432; done
real    0m1.178s
user    0m0.508s
sys     0m0.676s

Tenfold better!

Revision 4083 enables very basic rrdcached support.

The optimizations mentioned by janl are still valid, so they should be included in a future release.

I think that rrdcache + cgi graphing takes care of the main issue stated in the original ticket text. Updated the ticket text.

... Brian De Wolf has pointed out that consolidating all the dataseries of a plugin into one rrd file makes it problematic to add and delete data fields. If we take away this one thing and add that rrd 1.5 will add a rrd server we think that the optimizations mentioned here become obsolete. Closing the ticket as fixed. Get your 2.0 today! :-)

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