[rrd-users] rrdcached updating too fast

[Steve Shipway]

This is not a problem with rrdcached; it is because you are trying to update
too frequently.

 

rrdupdate to /usr/var/lib/collectd/rrd/localhost/cpu-7/cpu-idle.rrd at
1398215351 sec, 387208 usec
rrdupdate to /usr/var/lib/collectd/rrd/localhost/cpu-7/cpu-idle.rrd at
1398215351 sec, 395156 usec



The error message you give seems to indicate that rrdcached is being told to
update with the time not changing or even going backwards.  This most likely
indicates a problem with your script that does the update calls - this
should only happen once every step.  How long is a Step?  This depends on
how you created the RRD files, but usually it is 60s or 300s.

 

Try this command, which will tell you your Step size:

 

rrdtool info /usr/var/lib/collectd/rrd/localhost/cpu-7/cpu-idle.rrd | grep
step

 

The two lines above show you are trying to update twice at time 1398215351
(the usec do not matter).  This is way too quickly and gives the error.
Your update script should sleep by Step seconds before trying another
update.

 

Steve

 

Steve Shipway

s.shipway at auckland.ac.nz

 

From: rrd-users-bounces+s.shipway=auckland.ac.nz at lists.oetiker.ch
[mailto:rrd-users-bounces+s.shipway=auckland.ac.nz at lists.oetiker.ch] On
Behalf Of Hassan Noureddine
Sent: Wednesday, 23 April 2014 2:39 p.m.
To: rrd-users at lists.oetiker.ch
Subject: [rrd-users] rrdcached updating too fast

 

Hi all,

I was debugging the root cause of getting a long list of rrdcached  log
errors. like the on below. ( Illegal attempt to update in less than 1 sec.
step).

[err] collectd[3565]: rrdcached plugin: rrdc_update
(/usr/var/.../df-root/df_complex-free.rrd, [1386607176:21342183424.000000],
1) failed with status -1.

The rrdcached is configured to update every 10 seconds, but when running
scripts consuming  memory, and cpu usage, I can see single update for some
RRDs happening very frequent, causing long list of error logs.

I added debug codes to display update time, once I ran the scripts, I see
the updates occur much faster for some of the RRDs. I am listing son below.

rrdupdate to /usr/var/lib/collectd/rrd/localhost/cpu-7/cpu-idle.rrd at
1398215341 sec, 387199 usec
rrdupdate to /usr/var/lib/collectd/rrd/localhost/cpu-7/cpu-idle.rrd at
1398215351 sec, 387208 usec
rrdupdate to /usr/var/lib/collectd/rrd/localhost/cpu-7/cpu-idle.rrd at
1398215351 sec, 395156 usec
rrdcached plugin: rrdc_update
(/usr/var/lib/collectd/rrd/localhost/cpu-7/cpu-idle.rrd, [1398215351:36382],
1) failed with status -1.
rrdupdate to /usr/var/lib/collectd/rrd/localhost/cpu-7/cpu-idle.rrd at
1398215362 sec, 958488 usec
rrdupdate to /usr/var/lib/collectd/rrd/localhost/cpu-7/cpu-idle.rrd at
1398215371 sec, 393588 usec

rrdupdate to /usr/var/lib/collectd/rrd/localhost/cpu-7/cpu-steal.rrd at
1398215341 sec, 387544 usec
rrdupdate to /usr/var/lib/collectd/rrd/localhost/cpu-7/cpu-steal.rrd at
1398215351 sec, 387590 usec
rrdupdate to /usr/var/lib/collectd/rrd/localhost/cpu-7/cpu-steal.rrd at
1398215351 sec, 488583 usec
rrdcached plugin: rrdc_update
(/usr/var/lib/collectd/rrd/localhost/cpu-7/cpu-steal.rrd, [1398215351:0], 1)
failed with status -1.
rrdupdate to /usr/var/lib/collectd/rrd/localhost/cpu-7/cpu-steal.rrd at
1398215362 sec, 958920 usec
rrdupdate to /usr/var/lib/collectd/rrd/localhost/cpu-7/cpu-steal.rrd at
1398215371 sec, 393950 usec

Have this issue been addressed, and if not, which part of the code could be
causing it.

Thanks.

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