>> I've been running Cacti for quite some time now, and used RRDTool v1.2.15 all the way through 1.3.7, which is what we're currently using with Cacti.
>This discussion, at least if it is cacti-dependant, can be continued at the cacti forum if need be. I opened up a message on the cacti forum, but haven't gotten any resolution, which is why I posted here too. >> When I setup up RRA files that have NO consolidation, I'm still seeming to get consolidation in the graphs. >It may not actually be getting consolidated, but maybe it's the way the graphing algorithms 'squish' 8900 rows into a 500 pixel wide graph... >There's a good chance that your assumption is correct. This is what I called "graphical consolidation" at http://docs.cacti.net. >The "raw data" is still there but cannot be displayed. You may define a consolidation function for this as well (but cacti currently accepts only >the default = not yet implemented). >When zooming into the graph, the required granularity will show up as soon as you have "enough pixels" to display each data point. >For a better answer, the current rrd file definitions should be listed here. Here's my RRD defs: Hourly (5 Minute Average) 1 300 14400 Daily (5 Minute Average) 1 600 86400 Weekly (5 Minute Average) 1 2100 604800 Monthly (5 Minute Average) 1 9000 2678400 Yearly (5 Minute Average) 1 110000 33053184 >> I'm thinking there could be 1 of 2 things going on... cacti isn't calling RRDTool correctly, so the graphs are being consolidated, or RRDTool is >>interpolating the data, and mis-calculating the actual peak/average, as well as graphing it incorrectly, maybe due to a simplistic approach to >>making the data 'fit'. I dig through all the cacti code and it appears to be sending all the raw data to RRDtool, otherwise I'd expect the export >>to not have all the data points. >Find the call to rrdtool in lib/rrd.php to proove this. Actually I dig through rrd.php and pretty much disproved that cacti wasn't calling RRDtool correctly, it is indeed. I didn't see anything in the function that could be causing this, so I posted here. >Find the generated command when visiting "Graph Management" and switch to DEBUG. You may run this command from cli. I'm quite sure this will >exactly match your graph ;-) It does... but is still doesn't match the real data. >> If I plot the data in Excel, the graph represents the true data, with all the peaks preserved. > How do you force excel to draw this amount of data with 500 pixels only? Excel automatically graphs whatever size you want the graph to be, and anti-aliases/scales things appropriately. I don't know how it does it, just that if I graph the data in Excel it looks MUCH different than in RRDtool... The main point is that the MAX and MIN values in the raw data do NOT match the calculated MAX and MIN values on the graph. It appears as though RRDTool calc's these max/mins from its own 'squished' data. I think the issue here is how RRDtool interprets so many data points to create a graph that is only 500 pixels wide. I would think rather than averaging the data it should take the absolute value of the max as the point it plots, rather than taking an average of a number of points and plotting it. I would bet this is how Excel does it. _______________________________________________ rrd-users mailing list [email protected] https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users
