I decided to install Munin for my very first time and I think it really rocks and is exactly what I need but unfortunately it is only partially working. It has been running now for more than a few days and some of the graphs only show nan which are empty grids, I have only limited understanding of this so it is very likely that I may be going about this the wrong way since it is my first time using it.

From my endless searching so far I have managed to find a way of getting debug output from muning which unfortunately does not help me much because as far as I know there is no official munin forums so what ever you find on google is what you get.

debug output:

2011/10/02 19:00:05 [DEBUG] Lock /var/run/munin/munin-update.lock already exists, checking process
2011/10/02 19:00:05 [DEBUG] Lock contained pid '1322'
2011/10/02 19:00:05 [DEBUG] kill -0 1322 worked - it is still alive. Locking failed.
2011/10/02 19:00:05 [FATAL ERROR] Lock already exists: /var/run/munin/munin-update.lock. Dying.
2011/10/02 19:00:05  at /usr/share/perl5/Munin/Master/Update.pm line 128
[FATAL ERROR] Lock already exists: /var/run/munin/munin-update.lock. Dying.
 at /usr/share/perl5/Munin/Master/Update.pm line 128

I have found a ton of search results for "munin lock already exists" but no actual solutions.

Also my /var/log/munin/munin-update.log is filled with:

2011/10/02 20:15:02 [WARNING] Service diskstats_throughput on localhost.localdomain/localhost.localdomain:4949 returned no data for label xvda_rdbytes
2011/10/02 20:15:02 [WARNING] Service diskstats_throughput on localhost.localdomain/localhost.localdomain:4949 returned no data for label xvdb_wrbytes
2011/10/02 20:15:02 [WARNING] Service diskstats_latency on localhost.localdomain/localhost.localdomain:4949 returned no data for label xvdb_avgwait
2011/10/02 20:15:02 [WARNING] Service diskstats_latency on localhost.localdomain/localhost.localdomain:4949 returned no data for label xvda_avgwait
2011/10/02 20:15:02 [WARNING] Service diskstats_utilization.xvdb on localhost.localdomain/localhost.localdomain:4949 returned no data for label util
2011/10/02 20:15:02 [WARNING] Service diskstats_iops.xvda on localhost.localdomain/localhost.localdomain:4949 returned no data for label rdio
2011/10/02 20:15:02 [WARNING] Service diskstats_iops.xvda on localhost.localdomain/localhost.localdomain:4949 returned no data for label avgwrrqsz
2011/10/02 20:15:02 [WARNING] Service diskstats_iops.xvda on localhost.localdomain/localhost.localdomain:4949 returned no data for label wrio
2011/10/02 20:15:02 [WARNING] Service diskstats_iops.xvda on localhost.localdomain/localhost.localdomain:4949 returned no data for label avgrdrqsz
2011/10/02 20:15:02 [WARNING] Service diskstats_utilization.xvda on localhost.localdomain/localhost.localdomain:4949 returned no data for label util
2011/10/02 20:15:02 [WARNING] Service diskstats_utilization on localhost.localdomain/localhost.localdomain:4949 returned no data for label xvdb_util
2011/10/02 20:15:02 [WARNING] Service diskstats_utilization on localhost.localdomain/localhost.localdomain:4949 returned no data for label xvda_util
2011/10/02 20:15:02 [WARNING] Service diskstats_iops on localhost.localdomain/localhost.localdomain:4949 returned no data for label xvdb_rdio
2011/10/02 20:15:02 [WARNING] Service diskstats_iops on localhost.localdomain/localhost.localdomain:4949 returned no data for label xvda_wrio
2011/10/02 20:15:02 [WARNING] Service diskstats_iops on localhost.localdomain/localhost.localdomain:4949 returned no data for label xvda_rdio
2011/10/02 20:15:02 [WARNING] Service diskstats_iops on localhost.localdomain/localhost.localdomain:4949 returned no data for label xvdb_wrio

My instalation method was exactly as instructed in the tutorial http://library.linode.com/server-monitoring/munin/debian-6-squeeze which I find quite strange because some of the stats are stored and output correct graphs but others do not.

I have been fighting with this for over a day and I think it is time I ask for some advice to see if someone more experienced than me has had a similar issue and can point me in the right direction.

Sounds like it's taking longer than it should to poll. With one host, 5 minutes is probably more than enough time... I suspect it is hanging on a plugin that should be disabled.

Try:

munin-node-configure --suggest --remove-also --shell

This will output some shell script you can copy/paste to disable plugins that won't work and add other plugins that will work. Then, "service munin-node restart" to refresh.

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my exact output:

ln -s '/usr/share/munin/plugins/exim_mailqueue' '/etc/munin/plugins/exim_mailqueue'
ln -s '/usr/share/munin/plugins/exim_mailstats' '/etc/munin/plugins/exim_mailstats'
# The following plugins caused errors:
# ip_:
#       Nothing printed to stdout
#       No valid suggestions
# postfix_mailqueue:
#       Non-zero exit during autoconf (255)
# postgres_bgwriter:
#       Non-zero exit during autoconf (255)
# postgres_cache_:
#       Non-zero exit during autoconf (255)
# postgres_checkpoints:
#       Non-zero exit during autoconf (255)
# postgres_connections_:
#       Non-zero exit during autoconf (255)
# postgres_connections_db:
#       Non-zero exit during autoconf (255)
# postgres_locks_:
#       Non-zero exit during autoconf (255)
# postgres_querylength_:
#       Non-zero exit during autoconf (255)
# postgres_scans_:
#       Non-zero exit during autoconf (255)
# postgres_size_:
#       Non-zero exit during autoconf (255)
# postgres_transactions_:
#       Non-zero exit during autoconf (255)
# postgres_tuples_:
#       Non-zero exit during autoconf (255)
# postgres_users:
#       Non-zero exit during autoconf (255)
# postgres_xlog:
#       Non-zero exit during autoconf (255)
# tomcat_:
#       Non-zero exit during autoconf (127)

I know I should be enabling the exim plugin but I want to get the issues resolved first before adding more stuff.

As for the ones that would cause errors none of those are enabled.

If it's the same plugins erroring out each time, you can remove them from /etc/munin/plugins/ and that may clear it up. You might also find useful information in munin-node.log.

I find more than a few plugins enable themselves if they think they can get data, but few actually try getting test data to be sure, so your plight is not uncommon.

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I actually recently realized that there was also a munin-node.log file which had some really useful information in it. Searching the errors of the node log file seemed to have no results and eventually I came across a guy on a forum that said just uninstall it completely and reinstall it and that is exactly what I did. Now everything is working how it should be with no problems and I managed to add on additional plugins with no problem at all