[collectd] Help w/ exec plugin

Richard Hanschu richard.hanschu at canterbury.ac.nz
Sun Jun 27 23:34:18 CEST 2010

Hi All,

I have spent quite a few hours on this and my google-fu has been
defeated, so I turn to the experts for what feels like a disturbingly
simple problem.

I am having difficulties getting valid rrds with the exec plugin. SNMP
and local cpu plugins are working perfectly, so the general setup seems
fine. I have created a perl script to collect data from a embedded
webserver on a power meter which creates the following output every 60

tridiumJace/snmp/power-COE2 interval=60 N:468.73

I can confirm that the script is called and data is passed to collectd.
If I up the script interval to 1 sec, then the extra data will create
the following type of entries in the collectd log when too many data
points are feed to collectd for it's 10 min collection interval:

[2010-06-28 08:42:37] exec plugin: Prepending `PUTVAL' to this line:
tridiumJace/snmp/power-COE2 interval=60 N:452.65
[2010-06-28 08:42:37] uc_update: Value too old: name =
tridiumJace/snmp/power-COE2; value time = 1277671357; last cache update
= 1277671357;

A rrd file is created by collectd in the expected location. The problem
is that the resulting rrd has no data in it as shown by rrdtool dump:

                        <!-- 2010-06-27 12:43:00 NZST / 1277599380 -->
                        <!-- 2010-06-27 12:44:00 NZST / 1277599440 -->
                        <!-- 2010-06-27 12:45:00 NZST / 1277599500 -->
                        <!-- 2010-06-27 12:46:00 NZST / 1277599560 -->
                        <!-- 2010-06-27 12:47:00 NZST / 1277599620 -->

So I am guessing either this is either a very simple problem with my
input that I can't see, or something deeper about the exec plugin that
is beyond my skills to find and fix. Any clues?

Relevant part of Collectd.conf
LoadPlugin exec
<Plugin exec>
        Exec "rdh53:rdh53" "/opt/collectd/scripts/power_grabber.pl"

System Configuration:
collectd-4.10.0 built from source
RHEL 5.4
RRD packages:



  Richard Hanschu              Data Centre Operations Analyst
  Information Technology       Infrastructure Support Group
  University of Canterbury     Phone : 03 364 2987 x4149
  Private Bag 4800             Mobile: 027 445 6097
  Christchurch 8020            mailto:richard.hanschu at canterbury.ac.nz
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