<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>