I create graphs using a perl CGI(RRDs.pm) script that returns them when called via an <img src="/cgi-bin/blah.cgi"> tag. The problem is that I get a "phantom drop" at the far edge of the graph. Extrapolating from what I see when I do an rrdtool fetch, it seems a query against an RRDtool datafile includes as the last datapoint the NEXT point in time...
I store data on a five minute interval, and so say I query with a start of -34 hours and and end of now, now being 12:31pm, my last datapoint is 12:35pm, and is NAN. Unfortunately this, I believe, is the source of my "phantom drop"... a drop to zero at the most current right edge of the graph, which makes people think the port has just spiked downwards, when in fact it is fine. I use RRDtool 1.0.25, with a step of 300 and a heartbeat of 600. I use counters for data sources. I am polling switches via SNMP. If I change the endtime to "now-5minutes" it gets rid of the phantom drop... half of the time. My graph command is as follows: my @command = (); push( @command, "$full_file", "--title", "$title", "--imgformat", "$format" ); push( @command, "--lazy" ) if $lazy; push( @command, "--height", "$h" ) if $h; push( @command, "--width", "$w" ) if $w; push( @command, "--vertical-label", "$label" ) if $label; push( @command, "--start", "$start" ) if $start; push( @command, "--end", "$end" ) if $end; push( @command, "--base", "1024" ); push( @command, "--color", "BACK#0000ff", "--color", "FONT#ffff00" ); push( @command, qq/DEF:inoctets=$rrd_file:input:$gtype/ ); push( @command, qq/DEF:outoctets=$rrd_file:output:$gtype/ ); push( @command, qq/CDEF:inbits=inoctets,100000000,GT,0,inoctets,IF,8,*/ ); push( @command, qq/CDEF:outbits=outoctets,100000000,GT,0,outoctets,IF,8,*/ ); push( @command, qq/$gtypeout:outbits#9A556D:Outbound/ ); push( @command, qq/$gtypein:inbits#22556D:Inbound/ ); Suggestions? Michael Van Camp Programmer Alchemy Communications, Inc. Email: [EMAIL PROTECTED] Voice: 213-596-3000 x107 Yahoo: mikevc_la ICQ: 8412705 -- Unsubscribe mailto:[EMAIL PROTECTED] Help mailto:[EMAIL PROTECTED] Archive http://www.ee.ethz.ch/~slist/rrd-users WebAdmin http://www.ee.ethz.ch/~slist/lsg2.cgi
