On Fri, 2004-02-27 at 03:53, Eric Ho wrote: > Is it possible to write a CDEF to compute the average of some of the > samples from these 2 data sources and then graph this average value ? > By 'some samples', I mean samples from a certain period of time > in the past.
The short answer is yes, you can do this; but rrd-developers is not the right place to be asking this question. This belongs on -users. Here is a quick example of the DEFs, CDEF, and LINE you'll need. DEF:tx_rate_port1=port1.rrd:tx_bits:AVERAGE DEF:tx_rate_port2=port2.rrd:tx_bits:AVERAGE CDEF:tx_rate=tx_rate_port1,tx_rate_port2,+ LINE1:tx_rate:tx If you encounter circumstances when you have a new port added, which would throw a wrench into your graph by supplying UNKNOWN values for the period when the new port wasn't sampled, but is being requested by your graph command, you'll need some more CDEF-fu: CDEF:tx_rate=tx_rate_port1,UN,0,tx_rate_1,IF,tx_rate_port2,UN,0,tx_rate_2,IF,+ The above will convert UNKNOWN sample values in either port's sample data to valid samples with a value of 0. I use this when generating aggregate graphs for customer traffic, since I often have customers with multiple ports, and they tend to add/move/delete ports sometimes as their needs change, but still need useful graphs during those times. Once again, please post questions about rrdtool usage to the users list. The developers list is meant for folks with questions about the source (and I don't mean compiler problems, unless first explored on -users) because they're writing/contributing code to rrdtool.</rant> -- Jeff -- Unsubscribe mailto:[EMAIL PROTECTED] Help mailto:[EMAIL PROTECTED] Archive http://www.ee.ethz.ch/~slist/rrd-developers WebAdmin http://www.ee.ethz.ch/~slist/lsg2.cgi
