W3 Total Cache recommends Newrelic for WordPress application monitoring.

Newrelic provides detailed server and application monitoring. The PHP agent tracks which pages take a long time to render and which queries take a long time to run.

Install Newrelic

I installed the Newrelic agent and daemon using apt get as instructed on their website. (Bitnami have alternative instructions). Newrelic cannot find php.ini therefore after running the installer it is necessary to insert the Newrelic configuration file into

• /opt/bitnami/php/etc/php.ini

and manually copy in your licence key.

• restart Apache

and after about 5 mins data will start appearing in your dashboard at newrelic.com.

Configure W3TC Total Cache

To connect W3TC Total cache to your Newrelic account you must enter an API key into the W3TC settings for monitoring. This is not your license key! You can generate an API key in your Newrelic account. After you do this you will get some data in your W3TC dashboard. It will also say “you are not authorised..” but this is known bug and can be ignored. (I think).

Summary

When you first install you get 14 days free use of Pro. After that you get a wide range of monitoring for free and can upgrade to Pro (with stack traces etc) for $ 149 per month per server. This puts it beyond the reach of most bloggers for routine monitoring but could be worth it if you had an serious issue.