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List: rrd-users
Subject: Re: [rrd-users] RRDTool Fetch : Recover data with a different
From: Ryan Kubica <kubicaryan () yahoo ! com>
Date: 2011-09-25 7:09:04
Message-ID: 1316934544.98108.YahooMailNeo () web161614 ! mail ! bf1 ! yahoo ! com
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rrdtool will provide a 'consolidation on the fly' but not with fetch, only with \
xport.
use xport just like you would to create a graph (with the graph calls changing to \
XPORT instead of things like LINE, AREA, etc), and set the width ( max rows ) -- \
option -m to the number of rows you need between start and end. You will need to \
calculate this, but that's easy enough: (( end - start ) / step))
rrdtool does have the mildly annoying feature of wanting to return 10 rows though, so \
be aware of that when coding your functions and take it into account.
From the docs for rrd xport:
-m|--maxrows rows (default 400 rows)
This works like the -w|--width parameter of rrdgraph. In fact it is exactly the same, \
but the parameter was renamed to describe its purpose in this module. See rrdgraph \
documentation for details.
________________________________
From: Steve Shipway <s.shipway@auckland.ac.nz>
To: LE GONIDEC Romain <romain.le-gonidec@cg27.fr>; "'rrd-users@lists.oetiker.ch'" \
<rrd-users@lists.oetiker.ch>
Sent: Saturday, September 24, 2011 1:03 PM
Subject: Re: [rrd-users] RRDTool Fetch : Recover data with a different resolution of \
the RRA
RRDTool does not create a consolidation 'on the fly'. Therefore, if you need a \
particular average, you need ot add an RRA.
Why is this?
Because, RRDTool is optimised for rolling up averages. As averages are consolidated, \
data is lost, so it is quite likely that you cannot mathematically determine an \
average over a different resolution. Also, the colsolidation is the 'expensive' \
part, so by doing this progressivly as theupdates come in the performance is \
improved.
You specify a resolution in the FECTH or GRAPH because there may be more than one \
possible resolution at the requested time interval, if you have multiple RRAs that \
cover it. If an exact match is not available, RRDTool will use the closest available \
match.
Hope this helps,
Steve
Steve Shipway
University of Auckland ITS
UNIX Systems Design Lead
s.shipway@auckland.ac.nz
Ph: +64 9 373 7599 ext 86487
________________________________________
From: rrd-users-bounces+s.shipway=auckland.ac.nz@lists.oetiker.ch \
[rrd-users-bounces+s.shipway=auckland.ac.nz@lists.oetiker.ch] on behalf of LE GONIDEC \
Romain [romain.le-gonidec@cg27.fr]
Sent: Friday, 23 September 2011 2:47 a.m.
To: 'rrd-users@lists.oetiker.ch'
Subject: Re: [rrd-users] RRDTool Fetch : Recover data with a different \
resolution of the RRA
I am therefore obliged to add an RRA?
RRDtool can not calculate your own?
Why then specify a resolution. Only suffient timestamp.
_______________________________________________
rrd-users mailing list
rrd-users@lists.oetiker.ch
https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users
[Attachment #5 (text/html)]
<html><body><div style="color:#000; background-color:#fff; font-family:arial, \
helvetica, sans-serif;font-size:10pt"><div><span><br></span></div><div><span>rrdtool \
will provide a 'consolidation on the fly' but not with fetch, only with \
xport.</span></div><div><span><br></span></div><div><span>use xport just like you \
would to create a graph (with the graph calls changing to XPORT instead of things \
like LINE, AREA, etc), and set the width ( max rows ) -- option -m to the number of \
rows you need between start and end. You will need to calculate this, but \
that's easy enough: (( end - start ) / \
step))</span></div><div><span><br></span></div><div><span>rrdtool does have the \
mildly annoying feature of wanting to return 10 rows though, so be aware of that when \
coding your functions and take it into \
account.</span></div><div><span><br></span></div><div><span><br></span></div><div>From \
the docs for rrd xport:</div><div><span class="Apple-style-span" style="font-family: \
sans-serif; line-height: 24px; font-size: 16px; "><dt style="padding-top: 1em; \
font-weight: bold; "><a id="I_m___maxrows_rows__default_400_rows_" style="color: \
rgb(74, 113, 228); text-decoration: none; \
"><b>-m</b>|<b>--maxrows</b> <i>rows</i> (default 400 rows)</a></dt><dd \
style="margin-left: 1.5em; "><div style="margin-bottom: 0.2em; margin-top: 0.2em; \
">This works like the <b>-w</b>|<b>--width</b> parameter \
of <i>rrdgraph</i>. In fact it is exactly the same, but the parameter was \
renamed to describe its purpose in this module. \
See <i>rrdgraph</i> documentation for \
details.</div></dd></span></div><div><br></div><div><br></div><div><br></div><div \
style="font-size: 10pt; font-family: arial, helvetica, sans-serif; "><div \
style="font-size: 12pt; font-family: 'times new roman', 'new york', times, serif; \
"><font size="2" face="Arial"><hr size="1"><b><span \
style="font-weight:bold;">From:</span></b> Steve Shipway \
<s.shipway@auckland.ac.nz><br><b><span style="font-weight: \
bold;">To:</span></b> LE GONIDEC Romain <romain.le-gonidec@cg27.fr>; \
"'rrd-users@lists.oetiker.ch'" <rrd-users@lists.oetiker.ch><br><b><span \
style="font-weight: bold;">Sent:</span></b> Saturday, September 24, 2011 1:03 \
PM<br><b><span style="font-weight: bold;">Subject:</span></b> Re: [rrd-users] RRDTool \
Fetch : Recover data with a different resolution of the RRA<br></font><br>RRDTool \
does not create a consolidation 'on the fly'. Therefore, if you need a \
particular average, you need ot add an RRA.<br><br>Why is this?<br><br>Because, \
RRDTool is optimised for rolling up averages. As averages are consolidated, \
data is lost, so it is quite likely that you cannot mathematically determine an \
average over a different resolution. Also, the colsolidation is the 'expensive' \
part, so by doing this progressivly as theupdates come in the performance is \
improved.<br><br>You specify a resolution in the FECTH or GRAPH because there may be \
more than one possible resolution at the requested time interval, if you have \
multiple RRAs that cover it. If an exact match is not available, RRDTool will \
use the closest available match.<br><br>Hope this helps,<br><br>Steve<br><br>Steve \
Shipway<br>University of Auckland ITS<br>UNIX Systems Design Lead<br><a \
ymailto="mailto:s.shipway@auckland.ac.nz" \
href="mailto:s.shipway@auckland.ac.nz">s.shipway@auckland.ac.nz</a><br>Ph: +64 9 373 \
7599 ext 86487<br><br><br>________________________________________<br>From: \
rrd-users-bounces+s.shipway=<a ymailto="mailto:auckland.ac.nz@lists.oetiker.ch" \
href="mailto:auckland.ac.nz@lists.oetiker.ch">auckland.ac.nz@lists.oetiker.ch</a> \
[rrd-users-bounces+s.shipway=<a ymailto="mailto:auckland.ac.nz@lists.oetiker.ch" \
href="mailto:auckland.ac.nz@lists.oetiker.ch">auckland.ac.nz@lists.oetiker.ch</a>] on \
behalf of LE GONIDEC Romain [<a ymailto="mailto:romain.le-gonidec@cg27.fr" \
href="mailto:romain.le-gonidec@cg27.fr">romain.le-gonidec@cg27.fr</a>]<br>Sent: \
Friday, 23 September 2011 2:47 a.m.<br>To: '<a \
ymailto="mailto:rrd-users@lists.oetiker.ch" \
href="mailto:rrd-users@lists.oetiker.ch">rrd-users@lists.oetiker.ch</a>'<br>Subject: \
Re: [rrd-users] RRDTool Fetch : Recover data with a different \
resolution of the RRA<br><br>I am therefore obliged to add an \
RRA?<br>RRDtool can not calculate your own?<br>Why then specify a resolution. Only \
suffient timestamp.<br><br>_______________________________________________<br>rrd-users \
mailing list<br><a ymailto="mailto:rrd-users@lists.oetiker.ch" \
href="mailto:rrd-users@lists.oetiker.ch">rrd-users@lists.oetiker.ch</a><br><a \
href="https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users" \
target="_blank">https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users</a><br><br><br></div></div></div></body></html>
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