Added CentOS 7 installation, tweaked formatting

doc/Extensions/RRDCached.md

@@ -2,8 +2,8 @@
 
 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.
+### RRDCached installation CentOS 6
+This example is based on a fresh LibreNMS install, on a minimimal CentOS 6 installation.
 In this example, we'll use the Repoforge repository.
 
 ```ssh
@@ -33,7 +33,72 @@ chkconfig rrdcached on
 service rrdcached start
 ```
 
-Edit config.php to include:
+- Edit /opt/librenms/config.php to include:
 ```ssh
 $config['rrdcached']    = "unix:/var/run/rrdcached/rrdcached.sock";
 ```
+### RRDCached installation CentOS 7
+This example is based on a fresh LibreNMS install, on a minimimal CentOS 7.x installation.
+We'll use the epel-release and setup a RRDCached as a service.
+It is recommended that you monitor your LibreNMS server with LibreNMS so you can view the disk I/O usage delta.
+See [Installation (RHEL CentOS)][1] for localhost monitoring.
+
+- Install the EPEL and update the repos and RRDtool.
+```ssh
+yum install epel-release
+yum update
+yum update rrdtool
+```
+
+- Create the needed directories, set ownership and permissions.
+```ssh
+mkdir /var/run/rrdcached
+chown librenms:librenms /var/run/rrdcached
+chmod 755 /var/run/rrdcached
+```
+
+- Create an rrdcache service for easy daemon management.
+```ssh
+touch /etc/systemd/system/rrdcache.service
+```
+- Edit rrdcache.service and paste the example config:
+```ssh
+[Unit]
+Description=RRDtool Cache
+After=network.service
+
+[Service]
+Type=forking
+PIDFile=/run/rrdcached.pid
+ExecStart=/usr/bin/rrdcached -w 1800 -z 1800 -f 3600 -s librenms -j /var/tmp -l unix:/var/run/rrdcached/rrdcached.sock -t 4 -F -b /opt/librenms/rrd/
+RRDC_USER=librenms
+
+[Install]
+WantedBy=default.target
+```
+
+- Restart the systemctl daemon so it can recognize the newly created rrdcache.service. Enable the rrdcache.service on boot, and start the service.
+```ssh
+systemctl daemon-reload
+systemctl enable rrdcache.service
+systemctl start rrdcache.service
+```
+
+- Edit /opt/librenms/config.php to include:
+```ssh
+$config['rrdcached']    = "unix:/var/run/rrdcached/rrdcached.sock";
+```
+
+- Restart Apache
+```ssh
+systemctl restart httpd
+```
+
+Check to see if the graphs are being drawn in LibreNMS. This might take a few minutes.
+After at least one poll cycle (5 mins), check the LibreNMS disk I/O performance delta.
+Disk I/O can be found under the menu Devices>All Devices>[localhost hostname]>Health>Disk I/O
+Depending on many factors, you should see the Ops/sec drop by ~30-40%.
+
+
+[1]: http://librenms.readthedocs.org/Installation/Installation-(RHEL-CentOS)/#add-localhost
+"Add localhost to LibreNMS"