On Thursday 07 July 2011 07:15, Trent W. Buck wrote: > I rolled out collectd 4.8, running in each of about 20 LXC jails. > The I/O load was crippling the server, so I reduced polling with > "Interval 60" in each jail. > > However I would prefer to > > - poll every 10s (the default); > > - batch write RRDs, such that any given RRD is only written once > every ten minutes; and > > - distribute these writes more-or-less evenly over time, i.e. avoid > a huge I/O spike on the tenth minute. > > IIUC that means I should use this config: > > Interval 10 > CacheTimeout 600 > RandomTimeout 300 > > But this doesn't seem to be improving matters. Polling dm-25 (the > filesystem mounted at /var/lib/collectd) every ten seconds, before > the change: > > Device: tps Blk_read/s Blk_wrtn/s Blk_read > Blk_wrtn dm-25 163.70 16.80 1292.80 168 > 12928 dm-25 88.90 4.00 707.20 40 > 7072 dm-25 279.20 8.80 2224.80 > 88 22248 dm-25 302.40 8.80 2410.40 > 88 24104 dm-25 122.40 7.20 972.00 > 72 9720 dm-25 386.90 7.20 3088.00 > 72 30880 > > After the change: > > Device: tps Blk_read/s Blk_wrtn/s Blk_read > Blk_wrtn dm-25 33.20 11.20 254.40 112 > 2544 dm-25 292.10 12.00 2324.80 120 > 23248 dm-25 297.50 15.20 2364.80 > 152 23648 dm-25 41.90 8.80 326.40 > 88 3264 dm-25 428.30 4.00 3422.40 > 40 34224 dm-25 283.60 4.80 2264.00 > 48 22640 > > Is that wrong, or am I just expecting too much of buffered rrd > writes? > > _______________________________________________ > collectd mailing list > collectd@verplant.org > http://mailman.verplant.org/listinfo/collectd
Hi, I have been using the rrdcached plugin to force writes only every few minutes. However I think that rrdcached should also help balancing write load. Maybe someone else has better understanding about rrdcached. Toni _______________________________________________ collectd mailing list collectd@verplant.org http://mailman.verplant.org/listinfo/collectd