[rrd-users] Re: fetch & resolution

[Darren/Torin/Who Ever...]

Matthew Bostwick, in an immanent manifestation of deity, wrote:
>Hey Alex!
>Thanks for spending some time today with me.   Here's that snipit of logic
>you sent earlier.
>    "It works like this: If you want to store 1000 values
>     in 5 minute interval, rrdtool will allocate space
>     for 1000 data values and a header area."
>[...]
>    "This automatically limits the history to the last 1000 values."
>
>Okay, here's a dumb question.  How do I figure out how many rows there
>are in a give rrd data file?  It doesn't seem like I can dump by row, but
>just by date.  Heck I'd dump all and stick it into an array, if I could do
>that.

$ rrdtool info /var/lib/spong/rrd/database/perv.daft.com/disk-tmp.rrd
filename = "disk-tmp.rrd"
rrd_version = "0001"
step = 300
last_update = 988610989
[...elided...]
rra[0].cf = "AVERAGE"
rra[0].rows = 576
rra[0].pdp_per_row = 1
rra[0].xff = 5.0000000000e-01
[...]

This says that the first RRA (Round Robin Archive) has 576 rows with one
datapoint (pdp) per archive point.

rra[1].cf = "AVERAGE"
rra[1].rows = 576
rra[1].pdp_per_row = 6
rra[1].xff = 5.0000000000e-01

This RRA still has 576 rows but it puts 6 datapoints per archive point.
These are consolidated (cf) by averaging.  Up to half of the values to
consolidated may be unknown without the average returning unknown (xff).

Darren
-- 
<torin at daft.com><http://www.daft.com/~torin/> <torin at debian.org><perl at slut.org>
Darren Stalder/2608 Second Ave, @282/Seattle, WA 98121-1212/USA/+1-206-ELF-LIPZ
@		     Make a little hot-tub in your soul.		      @

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