[rrd-users] How to get MAX/MIN of non-rates?

Tony Mountifield tony at mountifield.org
Thu Mar 28 18:32:46 CET 2013

Hi, sorry if this is an FAQ. Please point me to a suitable URL if it is.

I'm trying to work out how to use GAUGE or something similar to log values
that are NOT rates. e.g. temperature, number of connections, or similar
quantity-valued properties.

I am using RRDs with a 5-min interval, with AVERAGE and MAX tables.

Let's say I log a value as follows:

00:00 => 0
00:01 => 5
00:02 => 0
00:03 => 0
00:04 => 0
00:05 => 0

Now, because the value was 5 for a fifth of the period, the average value
stored is 1, which is fine. However, the MAX table also has a value 1 stored,
instead of the value 5 that I expected.

It appears the CF for MAX doesn't apply to values within a period, but only
when periods are consolidated into longer periods.

I write values with their timestamps as and when they change, and had expected
RRD to keep the highest value written within the period as the stored MAX
value for the period.

Can anyone enlighten me how to achieve the above? Thanks!

Tony Mountifield
Work: tony at softins.co.uk - http://www.softins.co.uk
Play: tony at mountifield.org - http://tony.mountifield.org

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