[rrd-users] what is the output structures from rrdtool xport using RRDs

[Ashok Nair]

Hi,

what is the output structures from rrdtool xport using RRDs. There seems to be
starttime
step
number of rows
and two references to arrays. One array has nested references leading
to row data.

What is the other array for? Also does xport average if the requested
CDP's are less than what the selected resolution. For example if
requesting 10 CDP's (using M option) for last 30m and the RRA selected
has a resolution of 5 sec, and a CF of AVG, then does xport perform
considation to find 10 values and if yes what is the algorithm and how
deos it select the 10 timepoints.

Also my experience is that this is the only way you can extract a
numerical report
of DS's from RRD's. PRINT function in graphing doesn't let you touch
DS and CDEF. Is that a correct understanding?

Thanks

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[Morten Bjørnsvik]

Hi

If you want to export the data and do not have time to design an xml-parser,
you can use the old way of 'rrdtool info *.rrd' to find the consolidating functions
and 'rrdtool fetch *.rrd CF' to output it. You get all the DS tied to that CF.

%rrdtool fetch eth0.rrd MAX
timestamp eth0rx eth0tx

1138775820: 8.5033898305e+03 8.3728813559e+03
1138775880: 7.2485810873e+03 8.1029360007e+03
1138775940: 7.8926420765e+03 8.3899945355e+03
1138776000: 8.4928888889e+03 8.4288888889e+03
1138776060: 8.3976958569e+03 8.3682297552e+03
1138776120: 8.2467731777e+03 8.1029360007e+03
:

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MortenB


-----Original Message-----
From: rrd-users-***@list.ee.ethz.ch [mailto:rrd-users-***@list.ee.ethz.ch] On Behalf Of Ashok Nair
Sent: 1. februar 2006 02:35
To: rrd-***@list.ee.ethz.ch
Subject: [rrd-users] what is the output structures from rrdtool xport using RRDs

Also my experience is that this is the only way you can extract a numerical report of DS's from RRD's. PRINT function in graphing doesn't let you touch DS and CDEF. Is that a correct understanding?


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[Andreas Maus]

Hi.

Post by Morten Bjørnsvik
Hi
If you want to export the data and do not have time to design an xml-parser,
you can use the old way of 'rrdtool info *.rrd' to find the consolidating functions
and 'rrdtool fetch *.rrd CF' to output it. You get all the DS tied to that CF.
%rrdtool fetch eth0.rrd MAX
timestamp eth0rx eth0tx
1138775820: 8.5033898305e+03 8.3728813559e+03
1138775880: 7.2485810873e+03 8.1029360007e+03
1138775940: 7.8926420765e+03 8.3899945355e+03
1138776000: 8.4928888889e+03 8.4288888889e+03
1138776060: 8.3976958569e+03 8.3682297552e+03
1138776120: 8.2467731777e+03 8.1029360007e+03

Correct.
But it depends on your goals. If you want to do some
calculations with the data and/or you have lots of
sources (e.g. calculating the average cpu utilization for
a cluster of nodes or so) xport is the better choice.

For an example how to parse the output generated by xport
look at shared-demo.pl in the examples directory.

HTH,

Andreas.
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Dipl.-Ing. Andreas Maus science+computing ag
System Administration Hagellocher Weg 71-75
mail: ***@science-computing.de 72070 Tuebingen, Germany
tel.: [phone] www.science-computing.de

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[Ashok Nair]

Post by Morten Bjørnsvik
Hi
If you want to export the data and do not have time to design an xml-parser,
you can use the old way of 'rrdtool info *.rrd' to find the consolidating functions
and 'rrdtool fetch *.rrd CF' to output it. You get all the DS tied to that CF.
%rrdtool fetch eth0.rrd MAX
timestamp eth0rx eth0tx
1138775820: 8.5033898305e+03 8.3728813559e+03
1138775880: 7.2485810873e+03 8.1029360007e+03
1138775940: 7.8926420765e+03 8.3899945355e+03
1138776000: 8.4928888889e+03 8.4288888889e+03
1138776060: 8.3976958569e+03 8.3682297552e+03
1138776120: 8.2467731777e+03 8.1029360007e+03
--
MortenB

Thanks for poiting out shared-demo.pl.


Again going back to the example I cited, if you fetch from a rrd for
last 30m and the "chosen" RRA has a resolution of 5 sec, then you get
~360 CDP's.

If you wanted only 10 CDP's in that window( and I hope xport is
consolidating using the CF of RRA ? is that true) then xport with m
option is the only way I could find.

Why not let rrdtool take the burden of consolidating? That is, if it does

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