RRDCached Doc

- Doc to RRDCached installation on CentOS/RHEL

doc/Extensions/RRDCached.md

@@ -0,0 +1,40 @@
+# Setting up RRDCached
+
+This document will explain how to setup RRDCached for LibreNMS.
+
+### RRDCached installation
+This example is based on a fresh LibreNMS install, on a minimimal CentOS installation.
+In this example, we'll use the Repoforge repository.
+
+```ssh
+rpm -ivh http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.3-1.el6.rf.x86_64.rpm
+vi /etc/yum.repos.d/rpmforge.repo
+```
+- Enable the Extra repo
+
+```ssh
+yum update rrdttol
+vi /etc/yum.repos.d/rpmforge.repo 
+```
+- Disable both repo's
+
+```ssh
+service rrdcached start
+chkconfig rrdcached on
+vi /etc/sysconfig/rrdcached
+
+# Settings for rrdcached
+OPTIONS="-w 1800 -z 1800 -f 3600 -s librenms -j /var/tmp -l unix:/var/run/rrdcached/rrdcached.sock -t 4 -F -b /opt/librenms/rrd/"
+RRDC_USER=librenms
+
+mkdir /var/run/rrdcached
+chown librenms:librenms /var/run/rrdcached/
+chown librenms:librenms /var/rrdtool/
+chown librenms:librenms /var/rrdtool/rrdcached/
+service rrdcached restart
+```
+
+Edit config.php to include:
+```ssh
+$config['rrdcached']    = "unix:/var/run/rrdcached/rrdcached.sock";
+```