[collectd] collectd & rrdcached scalability issue

Bostjan Skufca bostjan at a2o.si
Sat Sep 8 04:36:16 CEST 2012

Hi Stefan,

I know this may not be the solution you are looking for, but:
How about using socket of rrdcached daemon and instructing it to flush the
data of immediate interest (rrds you are about to view)?
Works well for me on ganglia installation which uses rrdcached to cache up
to three hours of data...

What are your RRDcached settings? How much IOPS can you storage subsystem
handle? SSD as a fast-paced fix? Do you have a graph of IOPS for your
collectd host?


On 7 September 2012 09:16, Stefan Wiederoder <
stefanwiederoder at googlemail.com> wrote:

> Hello list,
> my current collectd (v4.10) installation is using rrdcached (rrdtool
> 1.4.4), which worked fine
> so far. But with the number or hosts growing beyond 1000 it seems to have
> a negative impact
> on my central collectd server.
> I´ve 37 GB of data (residing in a RAM-disk), plus 12 GB of journal data.
> Each hosts has a
> minimum of nine plugins activated, but max is only two or three more on
> some special boxes.
> the problem is that collectd data seems to lag "behind" the longer
> collectd/rrdcached is running.
> this accumulates up to three hours a day until the daily restart kicks in.
> An example, I see data
> from 12h when I look at graphs at 15h.
> this was not a problem with fewer hosts (< 900), it´s been getting worse
> with more and more hosts.
> I´ve only specified the number of write_threads so far (=16), but no other
> parameters.
> do you have any suggestion for me?
> thanks
> ,
> Stefan
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