[rrd-users] Re: RRD DS;heartbeat and MRTG

[Alex van den Bogaerdt]

> Given a five minute interval, we're keeping 600 1 interval avgs/maxs, 600
> 6 interval avgs/maxs, 600 24 interval avgs,maxs, and 732 288 interval
> avgs/maxs.
> 

IIRC MRTG is displaying 33 hours and 20 minutes of data by default
for the daily graph. This is 400 samples...

> Wouldn't it be better to specify the RRAs like this...
> 
> 	RRA:AVERAGE:0.5:1:288	(daily, 5 minute average)

...and therefore 288 is too low. MRTG logs even more than is specified
in 14all, it logs:

d)  "now"           to 600* 5 minutes before
w)  where (d) stops to 600*30 minutes before
m)  where (w) stops to 600* 2 hours   before
y)  where (m) stops to 732* 1 day     before

This makes a total of approximately 797 days.

To really log what MRTG logs, you should be doing:

d)  600 samples
w)  700 samples (600 * 30 minutes  +  600 * 5 minutes)
m)  775 samples (600 *  2 hours  + above)
y)  797 samples (732 *  1 day + above,  rounded up)

This is because RRDtool starts all RRAs at "now" and MRTG does not.

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