[rrd-users] bogus spikes with Infiniband traffic

Our Voltaire Infiniband switches (and perhaps others?) don't wrap their
traffic counters back to zero when they hit their maximum value.
Instead, they simply report "overflow" until a procedure is run to reset
them to zero.

On one of our mid-sized clusters, a handful of port counters are already
overflowing after a couple of hours, and more enter that state as the
day goes on.

To keep useful statistics generally available, we have a procedure that
resets the counters to zero once a day. Unfortunately, when we reset the
counters, rrdtool assumes that the counters have wrapped, and infers
very large traffic bursts through little-used ports.

I've been contemplating adding an `rrdtool reset` command that would
replace the last_ds value and timestamp with specified values, but would
prefer to learn that a better way to handle this already exists :)

TIA
/andy

--
Andy Riebs
HP -- Better Together
High Performance Computing -- XC Linux Software
<http://www.hp.com/go/clusters>
(w) +1.603.884.1521
andy.riebs@hp.com

My opinions are not necessarily those of HP

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