On 9 May 2014 16:37, Jonathan Kinred <[email protected]> wrote:
> I've done a fairly lengthy search and have had a glance over the code but > I still don't fully understand how the StoreRates works. I understand that > it takes COUNTER, DERIVE and ABSOLUTE types and converts then to GAUGE. > > To make it more specific, can someone help me understand the disk plugin > disk_ops/read metric, passed through the write_graphite plugin with > "StoreRates true". > > Looking at the disk plugin source code, it reads /proc/diskstats and > produces a disk_ops/read DERIVE value (e.g. 34500). > > The write_graphite plugin then calls uc_get_rate when StoreRates is true > and a GAUGE value is returned. > > My specific questions are: > * How does the conversion work? > * Does it know about the previous value (e.g. 340000) > * Does the Interval parameter play a role? > > Jonathan > With the help of #collectd on FreeNode I think I've worked out the confusion. It was based on my skimming over the DERIVE type (which are derived into a per second value). The other confusing part was the following section in the write_amqp plugin documentation which made me think the DERIVE value was going through some conversion to become a GAUGE: "Determines whether or not COUNTER, DERIVE and ABSOLUTE data sources are converted to a *rate* (i.e. a GAUGE value)." Is this correct? I think that DERIVE and ABSOLUTE are already "rates".
_______________________________________________ collectd mailing list [email protected] http://mailman.verplant.org/listinfo/collectd
