[collectd] collected 4.10.1 stops writing and high CPU

Yves Mettier ymettier at free.fr
Wed Jan 16 08:15:34 CET 2013


Issue #75 is the first think I'm thinking about.

Are you using rrdcached ?
If not, you should (but with so many rrds, I'm sure you are).

If yes, try to configure your collectd to *not* create rrds for some 
hours (maybe one or two days).
If this is better for you, you are probably experiencing issue #75.

Have a look at https://github.com/collectd/collectd/issues/75.
As far as I know, there is no "good" solution. Only some tips and 

If not issue #75, here are some ieads...

About your CPU shooting the roof, could you check if it works full time 
or if it is waiting for your disk ? (iostat should help).

Are you sure your disk is not 99% full (perfs are lower when a disk is 
nearly full).
Are you sure your disk is not broken ?

With iostat, if you have a FS dedicated to the rrd files, have you 
checked that it is that FS and not another that is working slowly ?

Note : I'm using 5.2, so I will not be able to help you better.


Le 2013-01-16 07:32, Jesse Reynolds a écrit :
> Hello
> We have a collectd server that is writing to about 24,000 RRD files,
> most of which are 15 MB each (with some at 30 MB and some at 45 MB),
> about 480 GB of RRD files in all.
> On occasion we are seeing disk writes drop right down to a trickle,
> and at the same time collectd's CPU shooting through the roof. Once
> collectd goes into this state it can be like this for hours, and the
> RRD files are mostly not being updated in this time. The only way to
> get things going again is to 'kill -9 <collectd's pids>' and start
> collectd again.
> The RRD files for data originating within this instance of collectd
> (and not coming via the network plugin) are not interrupted, so it is
> something to do with the network plugin, it seems.
> Has anyone got any advice on how we might chase this problem down
> further? We are on Ubuntu 12.04.
> Is it possible to peer into collectd to see if it's a problem with
> the network plugin, or the rrd plugin, or something else?
> Thank you
> Jesse
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> collectd at verplant.org
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