munin-ramfs

synchronise munin rrd files between persistent storage (disk) and non-persistent storage (ramfs) to reduce disk IO.

requirements

• rsync
• make
• munin

install

$ sudo make install
$ sudo /etc/alternatives/editor /etc/munin/munin.conf
$ sudo /etc/alternatives/editor /etc/default/munin-ramfs
$ sudo /usr/sbin/update-rc.d munin-ramfs defaults
$ sudo /etc/init.d/munin-ramfs start

features

• reduce disk IO to nearly zero.
• graphs are now generated onto volatile (ramfs) storage.
• transparently works with DRBD and pacemaker.

limitations

• up to 1 hour of rrd data files may be lost if init stop script is not executed.
• munin-cron-graph does not handle failover (*_ORIG location) if ramfs is not started/mounted.
• no error handling if rrd data total size exceeds available free ram.
• tested on Debian stable ("squeeze" 6.0) with DRBD and pacemaker.

author

David Sobon < d at sobon dot org >