<br>What I am trying to do is take two or more datasources with different time ranges and merge them into one CDEF for display (graph and legend.)<br><br>Example:<br><br> ds foo1 - start 7 days ago, end 6 days ago<br> ds foo2 - start 6 days ago, end 5 days ago<br> ds foo3 - start 5 days ago, end now<br><br> cdef is foo1 or foo2 or foo3<br><br>I have the correct time alignments for the adjacent time intervals, ie: foo1 ends 60 seconds before foo2 starts on a 60 second interval step.<br><br>I actually looked for an 'OR' operator - one which would just OR all the datapoints in the CDEF and use which ever was valid first ... and tried using the def1,UN,def2,def1,IF method.<br><br>No data shows in the graph or legend.<br><br>Url of output:<br><br>http://www.uploadyourimages.com/img/520921test.png<br><br>Here is the rrdtool command line for 2 datasources:<br><br>/apps/epic/rrdtool-1.2.99907080300/bin/rrdtool
graph<br>/apps/epic/apache-2.0.61/htdocs/test/test.png<br>-aPNG -se-2d -e1207628520<br>DEF:defwww100=/data01/epic/rrd/net/snmp/www100/.1.3.6.1.2.1.25.1.6.0.rrd:epoch:AVERAGE:start=1207369320:end=1207542060 <br>CDEF:def_uwww100=defwww100<br>DEF:defwww101=/data01/epic/rrd/net/snmp/www101/.1.3.6.1.2.1.25.1.6.0.rrd:epoch:AVERAGE:start=1207542120:end=1207628520 <br>CDEF:def_uwww101=defwww101<br>CDEF:ds_u0=def_uwww100,def_uwww101,+ <br>VDEF:vdsmax0=ds_u0,MAXIMUM<br>LINE1:ds_u0#ff0000:blah<br>"GPRINT:vdsmax0:Max %10.3lf %S"<br><br>In part I am wanting to use something like this for two purposes:<br><br>1) correct multi DS addition when one DS has 'nan' during the time interval. RRD can use the 'CDEF:def_u$def=def,UN,0,def,IF' method for graph lines, but for -some- reason the Last and Min VDEF's both show '0' if this is used ... or 'nan' if it's not used ... both not acceptable.<br><br>2) tracking an app stat between two hosts - ie: a maintenance which transitions the app
from host1 to host2.<br><br>3) I can create a merged RRD as a 'hack' - which is what I am doing for very important datasources, but that's expensive for too many datasources.<br><br><br>Thanks,<br><br>-Ryan<br><br><p> 
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