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Showing posts from December, 2013

Munin CPU Disk Throughput reduction load average

The System I run Munin 2.0.16 on CentOS 6 to monitor about 30 hosts.
I mostly monitor 25-30 parameters per host (this depends to the running services)
About half of the hosts are nearby (with a LAN latency) the other part is far (with about 250ms network latency).

The facts I have noticed "munin-graph" and "munin-html" took a long time. Long enough to overlap themselves if I keep the interval default (5 minutes).
I also noticed a huge "load average"
One of the most annoying thing is the Munin cronjob exiting with error (leading to a mail sent to the administrators) because a lock file (the one of the previous launch) still existing. This is very noise generator and lead to lower the importance of messages sent by munin...

Some solutions I was helped by this detailed post about Munin performance. And I decided to put both /var/lib/munin and /var/www/html/munin in tmpfs. In order to reduce the data loss when rebooting, I make an hourly dump to the disk fil…

Principe clé de Cfengine

Pour comprendre et utiliser CFengine correctement, il faut apréhender ses principes: CFengine permet de faire des promesses sur l'état du système.

Ainsi, avec CFEngine, on ne liste pas des actions mais des promesses.

On ne dit pas

Ajouter la ligne XXXXX à un fichierAjouter l'utilisateur YYYYLancer Apache

Mais plutot

S'assurer que la ligne XXX est présente dans le fichierS'assurer que YYYY existeS'assurer qu'Apache est lancé

De ce fait,

Si la ligne XXXX est supprimée du fichier, CFengine la remettraSi l'utilisateur YYYY se fait supprimer, CFengine le remettraSi Apache se fait tuer, CFEngine le relancera