New relic is a statistical monitoring tool for servers. This monitoring agent can keep an eye on things such as: CPU, Disk space, RAM usage and more. Alerts can be sent to your email address when your server gets close to its limits.
New relic is free! You are able to install this agent on a maximum of 2 servers for absolutely no cost! I highly recommend this tool.
You can sign up to new relic here: https://newrelic.com/signup
Once you have signed up you need to get your licence key. This can be located by navigating to the top right hand corner of the screen and clicking on the down arrow to locate Account Settings. You should now see a section on the right hand side of the screen with your Licence Key, make a note of this as you will need it later for the installation.
Once you have signed up you will need to install the agent on your server. The official guide is here: New Relic Install
rpm -Uvh https://yum.newrelic.com/pub/newrelic/el5/i386/newrelic-repo-5-3.noarch.rpm
rpm -Uvh https://yum.newrelic.com/pub/newrelic/el5/x86_64/newrelic-repo-5-3.noarch.rpm
You will now need to install the agent with the command
yum install newrelic-sysmond
You will now need to use the licence key you located at the beginning of the guide when you set up your account. You need to run the following command with your licence key
nrsysmond-config –set license_key=YOUR_LICENSE_KEY
Alternatively you are able to enter you licence key in the /etc/newrelic/nrsysmond.cfg file
You should now run the following command to start new relic
sudo /etc/init.d/newrelic-sysmond start
Your statistics should appear shortly (around 5 mins) under the servers tab in your new relic dashboard.