Get Maximum and Minimum value from rrd file generated by Cacti

Question

I have an rrd file in which traffic_in and out stats of interfaces are stored.

What i want is that i want Max and min values in certain time period.

I'm trying this command but it is giving me error ERROR: invalid rpn expression in: v,MAX

rrdtool graph -s 1537466100 -e 1537552237 DEF:v=lhr-spndc-7609_traffic_in_612.rrd:traffic_in:MAX CDEF:vm=v,MAX PRINT:vm:%lf

Can you please help to enter correct command & achieving desired Functionality?

Answer 1

You should be using VDEF for the definition of vm, not CDEF.

A CDEF is for transforming one or more data series created by either a DEF or CDEF into another series, ready for graphing or summarising.

A VDEF is for transforming a single data series into a single value via a consolodation function, such as to get the maximum value of a series over the entire graph. This is different from the function specified in a DEF, which only specifies how to consolodate a higher-granularity series into a lower-granularity series.