[rrd-users] Fetching 5 minute max values from RRDs

[William Cassis]

Hello,

I'm trying to extract the max values for each 5 minute sample from an
rrd file, but I've noticed that the values returned for max are the same
as the values for average:

rrdtool fetch fastethernet0_2.rrd AVERAGE -r 300 -s 12:00 -e 12:15
                            ds0                 ds1

1192647900: 9.4423089282e+04 3.4053380473e+04
1192648200: 7.0958851492e+04 3.3312245232e+04
1192648500: 4.5601612854e+04 1.5465940745e+04
1192648800: 7.6042505630e+04 1.5733790918e+04
rrdtool fetch fastethernet0_2.rrd MAX -r 300 -s 12:00 -e 12:15
                            ds0                 ds1

1192647900: 9.4423089282e+04 3.4053380473e+04
1192648200: 7.0958851492e+04 3.3312245232e+04
1192648500: 4.5601612854e+04 1.5465940745e+04
1192648800: 7.6042505630e+04 1.5733790918e+04

When I choose a resolution larger than 300 seconds (1800 seconds, for
example), the values returned for max and average are different (I'm
guessing because it's not using the 5 minute sample section of the rrd):

rrdtool fetch fastethernet0_2.rrd MAX -r 1800 -s 12:00 -e 13:00
                            ds0                 ds1

1192649400: 9.6160742247e+04 3.4053380473e+04
1192651200: 7.1751123418e+04 3.3134429366e+04
1192653000: 1.5926465216e+05 1.1399776686e+05

rrdtool fetch fastethernet0_2.rrd AVERAGE -r 1800 -s 12:00 -e 13:00
                            ds0                 ds1

1192649400: 7.2030585524e+04 2.3909270980e+04
1192651200: 5.4137476921e+04 2.3342711488e+04
1192653000: 1.2425490630e+05 6.5662137257e+04

MRTG used to store the average in/out and then the max in/out for each 5
minute sample in the log file.  Is there any way to get the 5 minute max
from an rrd file?

I'm using MRTG version 2.15.2 and rrdtool version 1.2.23 on FreeBSD 6.2.

Any help would be greatly appreciated.

Thank you!

Regards,

William Cassis
will at nextlevelinternet.com