g3vt wrote: > > On a somewhat related note.... Has anybody been able to combine > multiple datapoints in a perf graph and then plot that sum on the same > graph? Example- We have power distribution units that report load on > 3 different branches. We'd like to be able to graph the total load as > a sum of the 3 branches- (and even better alert on total load... but i > believe I read that's not possible at the moment) >
For a single device, with all the data points in the same template, that's actually pretty simple. Let's assume that you are able to create a graph that polots the three branches. I'll assume the data points are called branch_a, branch_b and branch_c, but names don't really matter so long as you are consistant. If you look at the graph commands, you'll see something like Code: DEF:branch_a-raw=rrdPath/branch_a.rrd:ds0:AVERAGE CDEF:banch_a-branch_a-raw LINE1Lbranch_a-raw#0000ff:branch a ... DEF:branch_b-raw=rrdPath/branch_b.rrd:ds0:AVERAGE CDEF:banch_b-branch_b-raw LINE1Lbranch_b-raw#0000ff:branch b ... DEF:branch_c-raw=rrdPath/branch_c.rrd:ds0:AVERAGE CDEF:banch_c-branch_c-raw LINE1Lbranch_c-raw#0000ff:branch c You can add custom graph points. So first, add a CDEF called all_branches and define the rpn as Code: branch_a-raw,branch_b-raw,+,branch_c-raw,+ that is just sum up the values from the rrd files. Then plot that using a line or area or what ever whose value is the name of the CDEF that is the sum. see http://oss.oetiker.ch/rrdtool/doc/rrdgraph_rpn.en.html for all the details. But in this case we're just summing three values, so the + operator does it all. If you don't want to graph the individual values, set them to display none. That will drop out the LINE defintions, but still make the values availiable. You should end up adding something like Code: CDEF:all_branches=branch_a-raw,branch_b-raw,+,branch_c-raw,+ LINE1:all_branches#FF0000:combined output To contrast this with my origional question, this one's easy because the paths of the RRD files are predictable, and fixed. The catchsI haven't figured out for combining devices are two: First how know either the rrdpaths or the names of the auto-generated DEFS in the final call to rrd_graph. Second, and likely the kicker, how dynamically generate the RPN for some variable set of devices (ie not for three devices I can name, but for 'all the devices in this device class'). -------------------- m2f -------------------- Read this topic online here: http://forums.zenoss.com/viewtopic.php?p=26157#26157 -------------------- m2f -------------------- _______________________________________________ zenoss-users mailing list [email protected] http://lists.zenoss.org/mailman/listinfo/zenoss-users
