Dear Dan, > I think you're missing the point.
just take a look at the number of posts alex makes. he does understand how rrdtool works, he know the code that makes it tick ... so if you tell him he is missing the point, chances are that he will not bother anymore help you understand how rrdtool works ... to your question. RRDtool tries hard to work correctly independant of the number of points it has to work with. So your graph, should turn out the same results, regardles of the number of samples that are available (withing reason). This means for example, that if you input data from an RRA that is using AVERAGE consolidation, that the graph will also use AVERAGE consolidation to reduce the data until it fits in the graph. If you use a MAX function over this, the MAX will return what you see in the graph. If you are interested in keeping the MAX of the data you have originally fed into RRDtool, you must store it in an RRA that has a MAX function attached. A little example: You have to 2 points in your RRA a: 10 b: 90 On the graph they map onto the same pixel. Depending on the consolidation function of the RRA, rrdtool will draw the pixle at the following positions avg: 50 min: 10 max: 90 on top of this you can use VDEF to calculate, but obviously the results will depend on the first round of consolidation that has already happened. >From a performance point of view, given your box has enough memory, you should be able to get about * 200-400 RRA updates a second per spindle Note that you can cheat this by increassing the amount of dirty buffers the OS tolerates as well as the ammount of time the dirty buffers can stay dirty. Especially if you run frequent updates this can be a neat strategy to increasse throughput dramatically (in cache updates, rrdtool 1.3 can do about 20k per second on a current box.) cheers tobi -- Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten http://it.oetiker.ch [EMAIL PROTECTED] ++41 62 213 9902 _______________________________________________ rrd-users mailing list [email protected] https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users
