Is StatsD used to aggregate metrics coming from CollectD (and possibly other tools)
something else entirely. If so what?
Best Answer
They are different things.
CollectD is statistics collection daemon. It periodically polls various sources (the plugin collection is quite exhaustive) for metrics. It can receive metrics as well. CollectD is well versed in collecting metrics from the system, various popular services (web servers, database servers, etc), as well as custom application metrics (this requires applications to generate those metrics). CollectD can do more things as well, but this is probably beyond scope of this question.
StatsD is event counter/aggregation service. It receives per-event timings and calculates and generates aggregated values. It is built to count/aggregate custom applications metrics. It only requires the application to send events, without any need for aggregations.
batsd is a daemon for aggregating and storing statistics, while batsd-dash is a configurable dashboard the present the data you have stored in batsd.
About batsd
Batsd is a ruby-based daemon for aggregating and storing statistics.
It targets "wireline" compatibility with Etsy's StatsD implementation,
which they described in a blog post.
Batsd differs from etsy's statsd implementation primarily in how it
stores data -- data is stored to a combination of Redis and flat files
on disk. You can read more about persistence in About: Persistence.
Batsd grew out of usage at 37signals, where it has been used for the
last year. An earlier form was inspired by quasor.
Best Answer
They are different things.
CollectD is statistics collection daemon. It periodically polls various sources (the plugin collection is quite exhaustive) for metrics. It can receive metrics as well. CollectD is well versed in collecting metrics from the system, various popular services (web servers, database servers, etc), as well as custom application metrics (this requires applications to generate those metrics). CollectD can do more things as well, but this is probably beyond scope of this question.
StatsD is event counter/aggregation service. It receives per-event timings and calculates and generates aggregated values. It is built to count/aggregate custom applications metrics. It only requires the application to send events, without any need for aggregations.
CollectD supports StatsD as an input since version 5.4, so there is no need to run separate daemon: https://collectd.org/wiki/index.php/Plugin:StatsD