http://munin-monitoring.org/wiki/rrdcached
http://munin.jp/wiki/rrdcached
https://www.tumfatig.net/20150731/enabling-rrdcached-for-munin-on-openbsd/
http://pocketstudio.jp/log3/2013/07/31/bring_back_io_with_munin_and_rrdcached/
https://github.com/munin-monitoring/munin/blob/master/plugins/node.d.debug/rrdcached
freebsd
vi /etc/rc.conf rrdcached_enable="YES" rrdcached_flags="-s munin -l /var/run/rrdcached.sock -p /var/run/rrdcached.pid -w 1800 -z 1800 -f 3600" vi /etc/group munin:*:842:www vi /usr/local/etc/munin/munin.conf rrdcached_socket /var/run/rrdcached.sock
munin plugin
cd /usr/local/share/munin/plugins/ wget https://raw.githubusercontent.com/kurita0/munin-freebsd/master/rrdcached chmod +x rrdcached ln -s /usr/local/share/munin/plugins/rrdcached /usr/local/etc/munin/plugins/ vi /usr/local/etc/munin/plugin-conf.d/rrdcached.conf env.peer /var/run/rrdcached.sock
