[rrd-users] Question about the historical complaint about irregular data gone missing

John Allspaw allspaw at gmail.com
Tue Dec 22 14:51:27 CET 2009

1st: I'm a huge fan of rrd. Thanks Tobias!
2nd: After hearing some various gripes about rrd from colleagues, I came
upon this reasoning for a metrics collection project who started with RRD as
its data store, then found a lack and so created its own:


Their reasons for not using rrd is, (from
http://graphite.wikidot.com/faq#toc8) -

"The first reason is that RRD is designed under the assumption that data
will always be inserted into the database on a regular basis, and this
assumption causes RRD behave undesirably when given irregularly occurring
data. Graphite was built to facilitate visualization of various application
metrics that do not always occur regularly, like when an uncommon request is
handled and the latency is measured and sent to Graphite. Using RRD, the
data gets put into a temporary area inside the database where it is not
accessible until the current time interval has passed _and_ another value is
inserted into the database for the following interval. If that does not
happen within an allotted period of time, the original data point will get
overwritten and is lost. Now for some metrics, the lack of a value can be
correctly interpreted as a value of zero, however this is not the case for
metrics like latency because a zero indicates that work was done in zero
time, which is different than saying no work was done. Assuming a zero value
for latency also screws up analysis like calculating the average latency,

Is this still the case? IIRC, missing data due to irregularity isn't an
issue, given the right resolution in the definitions, right?

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