Hi Steve. Thanks a lot for the ADDNAN hint. I changed summarization formula to: CDEF:sum_in=in1,in3,ADDNAN,in4,ADDNAN,in5,ADDNAN,...... CDEF:sum_out=out1,out3,ADDNAN,out4,ADDNAN,out5,ADDNAN,......
Now it works great. 2013/11/6 Steve Shipway <[email protected]> > Looks like a race condition with regard to ‘Current’ value. > > > > For example, the RRD ‘buckets’ (step size) may be of size 5min. Thus, > they run 12:00-12:05, 12:05-12:10, etc etc > > > > If the current time is 12:01, but your data comes in at 12:04, then the > ‘current’ value is ‘unknown’ – since there is no data for the current > bucket. > > > > Not knowing your RRD configuration, heartbeat, step, etc I can’t say for > sure, but I have seen this happen many times in RRD graphs. > > > > The way around it is to cheat J. You can define a CDEF that uses > something like “x,UN,PREV,x,IF” and then use this for your ‘Current’ > calculation; though this will hide when a DS is really unknown. > > > > Otherwise, if you know the graph is base at ‘now’, and your step is 5 min, > then try “NOW,TIME,-,300,LT,x,UN,+,2,EQ,PREV(x),x,IF” > > > > This says “If this data point is <5min old, and is unknown, then take the > previous value, else take the current value” > > > > You may also want to take a look at the ADDNAN function for your sum_in > and sum_out instead of all the UN,IF etc. > > > > Steve > > > ------------------------------ > > *Steve Shipway* > > ITS Unix Services Design Lead > > University of Auckland, New Zealand > > Floor 1, 58 Symonds Street, Auckland > > *Phone: +64 (0)9 3737599 ext 86487 > <%2B64%20%280%299%203737599%20ext%2086487>* > > *DDI: +64 (0)9 923 6487 <%2B64%20%280%299%20923%206487>* > > *Mobile: +64 (0)21 753 189 <%2B64%20%280%2921%20753%20189>* > > *Email: [email protected] <[email protected]>* > > P Please consider the environment before printing this e-mail : 打印本 > 邮件，将减少一棵树存活的机会 > > > > *From:* [email protected][mailto: > [email protected]] *On Behalf > Of *Stanislav Datskevich > *Sent:* Wednesday, 6 November 2013 4:34 a.m. > *To:* [email protected] > *Subject:* [rrd-users] Strange behavior of rrdgraph with data > summarization from multiple RRDs by CDEF > > > > Hello, list! > 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: > > CDEF:sum_in=in1,UN,0,in1,IF,in3,UN,0,in3,IF,+,in4,UN,0,in4,IF,+,<others>,8,* > > CDEF:sum_out=out1,UN,0,out1,IF,out3,UN,0,out3,IF,+,out4,UN,0,out4,IF,+,<others>,8,* > 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. > Result is very strange: http://noc.nek0.net/configs/graph_good.png shows > graph on even minutes (i.e. 14:16 ), > http://noc.nek0.net/configs/graph_bad.png shows graph on odd minutes > (14:17). Look at the graph legend: it shows now is 0.00 bps traffic. > > Workaround is to not check first variable in CDEF for unknown, like this: > CDEF:sum_in=in1,in3,UN,0,in3,IF,+,in4,UN,0,in4,IF,+,<others>,8,* > CDEF:sum_out=out1,out3,UN,0,out3,IF,+,out4,UN,0,out4,IF,+,<others>,8,* > With this formula, it will show last value correct regardless of current > minute. > > RRDs updates every minute, at first 2-3 seconds of the minute. > > Can somebody explain this please? > I will appreciate any help. > My whole rrdgraph expression also is in attach. >
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