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</o:shapelayout></xml><![endif]--></head><body lang=EN-NZ link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Looks like a race condition with regard to ‘Current’ value.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>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<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>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.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>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.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The way around it is to cheat </span><span style='font-size:11.0pt;font-family:Wingdings;color:#1F497D'>J</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>. 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. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>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”<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>This says “If this data point is <5min old, and is unknown, then take the previous value, else take the current value”<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>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.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Steve<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div class=MsoNormal align=center style='text-align:center'><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><hr size=2 width="100%" align=center></span></div><p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Steve Shipway</span></b><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p></o:p></span></b></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>ITS Unix Services Design Lead<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>University of Auckland, New Zealand<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Floor 1, 58 Symonds Street, Auckland<o:p></o:p></span></p><p class=MsoNormal><i><span style='font-size:10.0pt;font-family:"Calibri","sans-serif";color:#595959'>Phone: +64 (0)9 3737599 ext 86487<o:p></o:p></span></i></p><p class=MsoNormal><i><span style='font-size:10.0pt;font-family:"Calibri","sans-serif";color:#595959'>DDI: +64 (0)9 923 6487<o:p></o:p></span></i></p><p class=MsoNormal><i><span style='font-size:10.0pt;font-family:"Calibri","sans-serif";color:#595959'>Mobile: +64 (0)21 753 189<o:p></o:p></span></i></p><p class=MsoNormal><i><span style='font-size:10.0pt;font-family:"Calibri","sans-serif";color:#595959'>Email: <a href="mailto:s.shipway@auckland.ac.nz"><span style='color:#595959'>s.shipway@auckland.ac.nz</span></a><o:p></o:p></span></i></p><p class=MsoNormal><span lang=EN-GB style='font-size:18.0pt;font-family:Webdings;color:green'>P</span><span lang=EN-GB style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:blue'> </span><span lang=EN-GB style='font-size:10.0pt;font-family:"Arial Narrow","sans-serif";color:green'>Please consider the environment before printing this e-mail</span><span lang=EN-GB style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:blue'> : </span><span lang=ZH-TW style='font-size:10.0pt;font-family:"MS Gothic";color:green'>打印本</span><span lang=ZH-TW style='font-size:10.0pt;font-family:MingLiU;color:green'>邮件，将减少一棵树存活的机会</span><span lang=EN-GB style='font-size:7.5pt;font-family:"Verdana","sans-serif";color:navy'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div style='border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt'><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> rrd-users-bounces+s.shipway=auckland.ac.nz@lists.oetiker.ch [mailto:rrd-users-bounces+s.shipway=auckland.ac.nz@lists.oetiker.ch] <b>On Behalf Of </b>Stanislav Datskevich<br><b>Sent:</b> Wednesday, 6 November 2013 4:34 a.m.<br><b>To:</b> rrd-users@lists.oetiker.ch<br><b>Subject:</b> [rrd-users] Strange behavior of rrdgraph with data summarization from multiple RRDs by CDEF<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>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.<o:p></o:p></p></div></div></div></body></html>