[rrd-users] "wrong" highest resolution?

[Simon Hobson]

Marco Marongiu wrote:

>In fact, if my understaning was right, rra[0] is the archive with the
>highest resolution, being:
>
>rra[0].pdp_per_row = 1
>rra[1].pdp_per_row = 6
>rra[2].pdp_per_row = 2
>rra[3].pdp_per_row = 288
>
>What happens is that the archive returns data as if the highest
>resolution was 600, not 300 (this happens whether I use -r or not, and
>is concordant with the manual):
>
>$ rrdtool fetch /tmp/x*.rrd AVERAGE -s 1288566000 -e 1291158000 -r 300 |
>head

OK, there is a bit of information missing here - how many 
consolidated data points are being kept for each resolution ?

If I point out that (1291158000 - 1288566000)/300 is 8640, and then 
direct you to the lines showing "rra[n].rows = " below, does that 
help ?

>filename = "/tmp/x01-03_cpu_idle_3677.rrd"
>rrd_version = "0003"
>step = 300
>last_update = 1290615226
>ds[cpu_idle].type = "COUNTER"
>ds[cpu_idle].minimal_heartbeat = 600
>ds[cpu_idle].min = 0,0000000000e+00
>ds[cpu_idle].max = 1,0000000000e+04
>ds[cpu_idle].last_ds = "258249960"
>ds[cpu_idle].value = 3,5498196667e+05
>ds[cpu_idle].unknown_sec = 0
>rra[0].cf = "AVERAGE"
>rra[0].rows = 600
>rra[0].cur_row = 599
>rra[0].pdp_per_row = 1
>rra[0].xff = 5,0000000000e-01
>rra[0].cdp_prep[0].value = NaN
>rra[0].cdp_prep[0].unknown_datapoints = 0
>rra[1].cf = "AVERAGE"
>rra[1].rows = 700
>rra[1].cur_row = 699
>rra[1].pdp_per_row = 6
>rra[1].xff = 5,0000000000e-01
>rra[1].cdp_prep[0].value = 3,2111851609e+03
>rra[1].cdp_prep[0].unknown_datapoints = 0
>rra[2].cf = "AVERAGE"
>rra[2].rows = 9216
>rra[2].cur_row = 9215
>rra[2].pdp_per_row = 2
>rra[2].xff = 5,0000000000e-01
>rra[2].cdp_prep[0].value = 0,0000000000e+00
>rra[2].cdp_prep[0].unknown_datapoints = 0
>rra[3].cf = "AVERAGE"
>rra[3].rows = 797
>rra[3].cur_row = 796
>rra[3].pdp_per_row = 288
>rra[3].xff = 5,0000000000e-01
>rra[3].cdp_prep[0].value = 3,1040640971e+05
>rra[3].cdp_prep[0].unknown_datapoints = 0


In other words, you are asking for a graph of 8640 values from a data 
set that only contains 600. The 'best' data set that contains the 
number of data points (or rather, covers the time interval) asked for 
is the third which consolidates 2 PDPs into a CDP with a resolution 
of 600s.


-- 
Simon Hobson

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