[rrd-users] "concatenating" RRDs at graphing time?
william at shallum.net
Fri Jul 2 15:31:28 CEST 2010
I'm trying to virtually "concatenate" two RRDs together at graphing time. Let's say there are 3 points in time a, b, and c where a < b < c. I want to use the data in a.rrd between a and b, and the data in b.rrd between b and c.
"rrd graph" is called with the --start option set to a, and the --end option set to c. The defs are as follows:
This works, I can graph data_a and data_b separately.
Now, to combine them into one value:
Unfortunately, this does not work except when time = b (the only point where there is both data_a and data_b).
What works is:
What I want to know is, why can't the first CDEF (the one with ADDNAN) work? The solution with the IF would be longer if there are 3 or 4 RRDs to use.
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