[rrd-users] Question about multiple DS's in a RRD

Christian_Lair at i2.com Christian_Lair at i2.com
Mon Mar 22 21:50:23 MET 2004

I'm trying to create a rrd that will keep track of some stats for unix 
machines. I'm tracking load avg, cpu load, and vm load, the data is being 
collected via SNMP and stored in a colon separated file, updated every 15 
mins. The whole purpose of putting the data into a RRD is to create 1 
graph showing all 3 items. I've created a RRD using this command:
rrdtool create /data/load_avg.rrd --start 1072936800 \
 --step 900 \
 DS:load:GAUGE:900:0.0:U \
 DS:cpu:GAUGE:900:0:100 \ 
 DS:vm:GAUGE:900:0:U \

I'm using Perl to parse the datafile and update the RRD. I started out 
just updating the load avg and that worked just fine. I've now decided to 
take another step forward and update the cpu and vm using this code:

open (DATA,"/data/rrd/datafile");

while (<DATA>) {
mem,$os,$cpuspeed,$fs,$version) = split (/:/);

  my $date = join (':',$time,$min,$seconds);
  $time = &UnixDate($date,"%s");

  my($min1,$min10,$min15)= split (/,/,$load);

  RRDs::update ("$rrd", "--template", "load", "$time:$min15");
  my $ERR=RRDs::error;
  die "ERROR while updating rrd: $ERR\n" if $ERR;

RRDs::update ("$rrd", "--template", "cpu", "$time:$cpuload");
  my $ERR=RRDs::error;
  die "ERROR while updating rrd: $ERR\n" if $ERR;

RRDs::update ("$rrd", "--template", "vm", "$time:$vmem");
  my $ERR=RRDs::error;
  die "ERROR while updating rrd: $ERR\n" if $ERR;
close DATA;

Now I'm getting the error: ERROR while updating rrd: illegal attempt to 
update using time 1072937826 when last update time is 1072937826 (minimum 
one second step).

I assume its because of the second and third RRDs::update statements. How 
can I update all three DS's in the RRD when they have the same update 

Christian Lair

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