<div dir="ltr">Hello, list!<br>I've found a strange behavior of rrdgraph when I trying to summarize traffic data from multiple RRDs. I use this CDEF expression to summarize traffic:<br>CDEF:sum_in=in1,UN,0,in1,IF,in3,UN,0,in3,IF,+,in4,UN,0,in4,IF,+,<others>,8,*<br>
CDEF:sum_out=out1,UN,0,out1,IF,out3,UN,0,out3,IF,+,out4,UN,0,out4,IF,+,<others>,8,*<br>Point is to check every variable to 'unknown' value and replace it with 0, then sum with previous values, and at last multiple sum by 8 to get bits instead of bytes.<br>
Result is very strange: <a href="http://noc.nek0.net/configs/graph_good.png" target="_blank">http://noc.nek0.net/configs/graph_good.png</a> shows graph on even minutes (i.e. 14:16 ), <a href="http://noc.nek0.net/configs/graph_bad.png" target="_blank">http://noc.nek0.net/configs/graph_bad.png</a> shows graph on odd minutes (14:17). Look at the graph legend: it shows now is 0.00 bps traffic.<br>
<br>Workaround is to not check first variable in CDEF for unknown, like this:<br>CDEF:sum_in=in1,in3,UN,0,in3,IF,+,in4,UN,0,in4,IF,+,<others>,8,*<br>CDEF:sum_out=out1,out3,UN,0,out3,IF,+,out4,UN,0,out4,IF,+,<others>,8,*<br>
With this formula, it will show last value correct regardless of current minute.<br><br>RRDs updates every minute, at first 2-3 seconds of the minute.<br><br>Can somebody explain this please?<br>I will appreciate any help.<br>
My whole rrdgraph expression also is in attach.<br></div>