[rrd-users] newbie question

[marco at nucleus.it]

Hi to all,
i'm tryng to create a simple graph with rrd.
I already read some tutorials but i need some help.
I'm using varnish and i want to get a stat for minute about cache hit
and misses.

The rrd was created like that:

rrdtool create varnishtest.rrd --start now --step 60
DS:varnish_hits:COUNTER:120:0:U DS:varnish_misses:COUNTER:120:0:U
RRA:AVERAGE:0.5:1:1440

Hits and misses are values that grow or remain the same  every minute:
ex from the beginning:
N:hits:misses

N:0:0
N:0:0
N:1:1	1 hit 1 miss
N:1:1
N:22:9	22 hit 9 miss
N:22:22
N:22:22

With 
rrdtool fetch  varnishtest.rrd AVERAGE i have this values:
1375347420: -nan -nan
1375347480: -nan -nan
1375347540: -nan -nan
1375347600: 0.0000000000e+00 0.0000000000e+00
1375347660: 1.6285472960e-02 1.6285472960e-02
1375347720: 3.8119370619e-04 3.8119370619e-04
1375347780: 3.4174780290e-01 1.3018963920e-01
1375347840: 8.2521970953e-03 2.1462575314e-01
1375347900: 0.0000000000e+00 5.1846076597e-03
1375347960: 0.0000000000e+00 0.0000000000e+00
1375348020: 0.0000000000e+00 0.0000000000e+00

rrdtool   graph varnishtest.png  --start=-40m --imgformat=PNG
--title='Varnish' --vertical-label='requests/s'
DEF:b="varnishtest.rrd":varnish_hits:AVERAGE LINE1:b#06F33E:Hits
DEF:c="varnishtest.rrd":varnish_misses:AVERAGE LINE1:c#F30000:Misses


In the graph attached i have strange spikes , 200 ? 300 ???
What i'm doing wrong ?


thanks for the support
Marco
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