Thanks Tobi - that is perfect. And I am sorry that I am the 1000thst person to ask this queston! :)
> -----Original Message----- > From: Tobias Oetiker [mailto:[EMAIL PROTECTED] > Sent: Wednesday, November 19, 2008 9:44 AM > To: Mark Easton > Cc: [email protected] > Subject: RE: [rrd-users] How Does RRDTool Produce Chart with > MANY Data Points > > Tomorrow Mark Easton wrote: > > > Hi Tobi, > > > > I think you have missed my point. Please ignore the ave, max, min > > stuff I spouted on about (I edited my post online). > > > > The RRA I am using in my graph has no consolidation. It > presents for > > one month, about 40,000 points (60 second readings from my > sensor - my > > step is 60). ie > > > > RRA:AVERAGE:0.5:1:40320 (I assume that AVERAGE, MAX, MIN > of 1 value will > > all be the same??) > > > > My question is that when I ask RRDTool to produce a graph for this > > does it just plot all 40320 points or does it do some optimisations > > based on the size of the graphic being produced? For 12 months, it > > would need to plot 524,000 odd points. > > Mark, > > I think I have understood you perfectly (you are only about > to 1000thst person to ask this question). But I guess I have > still not reached the point where I am able to explain this > to people so that they understand in the first round ... > > If you plit 10'000 points to a chart 1000 pixel wide, then > rrdtool does NOT plot every point, but it takes groups of 10 > points and figures out where to draw the pixel in the graph. > The method it uses for this process it the same that was > asigned to the RRA unless you add a reduce optino to the DEF > line when pulling the data in. > > Since you did not add a reduce option you see the average of > 10 point plotted. > > For performance reasons it makes sense to have additional > RRAs roughly matching the graph resolutions people will be looking at. > > hope this helps > tobi > > > if you like, I can repeat for you what I wrote yesterday. > > > > Cheers, > > Mark > > > > > -----Original Message----- > > > From: Tobias Oetiker [mailto:[EMAIL PROTECTED] > > > Sent: Tuesday, November 18, 2008 7:53 PM > > > To: Robert Easton > > > Cc: [email protected] > > > Subject: Re: [rrd-users] How Does RRDTool Produce Chart with MANY > > > Data Points > > > > > > Hi Robert, > > > > > > Yesterday Robert Easton wrote: > > > > > > > > > > > Hi, > > > > > > > > If I ask RRDTool to plot a chart with 10,000 data > points it does > > > > so very fast. What is RRDTool doing in the code? It appears to > > > me that it > > > > is averaging or smoothing the data. Is that right? > > > > > > > > I was actually plotting readings from a temperature sensor > > > taken every > > > > minute for one week. So that is 60 x 24 x 7 = 10080 data > > > points. In a > > > > patrticular day the temperature might have a min of 8 and a > > > max of 24, > > > > but the resulting chart did not manage to show that min and > > > that max > > > > in a particular day. > > > > > > > > So what does it do? > > > > > > rrdtool uses the same consolidation function that was > defined in the > > > RRA to further consolidate the data so that it matches > the resoltion > > > of the graph ... if you want to see min and max, setup additional > > > rras with MIN and MAX consolidation functions > > > > > > OR > > > > > > use the reduce option in the DEF line to override the reduce > > > function with MIN or MAX respectively. > > > > > > cheers > > > tobi > > > > > > > > > > > Thanks, > > > > Mark > > > > > > > > > > -- > > > Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, > > > Switzerland http://it.oetiker.ch [EMAIL PROTECTED] ++41 62 775 > > > 9902 / sb: -9900 No virus found in this incoming message. > > > Checked by AVG - http://www.avg.com > > > Version: 8.0.175 / Virus Database: 270.9.4/1795 - Release > > > Date: 11/17/2008 5:24 PM > > > > > > > > > -- > Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, > Switzerland http://it.oetiker.ch [EMAIL PROTECTED] ++41 62 775 > 9902 / sb: -9900 No virus found in this incoming message. > Checked by AVG - http://www.avg.com > Version: 8.0.175 / Virus Database: 270.9.6/1797 - Release > Date: 11/18/2008 11:23 AM > _______________________________________________ rrd-users mailing list [email protected] https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users
