I created this HOWTO while building a new development environment today. The intention is to take a single Apache2/Varnish/MySQL environment and scale it to two servers, with one effectively a “hot-standby” – increase redundancy and continuity whilst maintaining current performance. This HOWTO is based on Linux Debian-76-wheezy-64-minimal 3.2.0-4-amd64 #1 SMP Debian 3.2.60-1+deb7u3 x86_64
Section #1: Set up MySQL Master/Master Replication
First, we’ll set up MySQL master to master replication. In this configuration, data can be written and read from either host. Bear in mind that issues may exist with autoincrement fields when written to at the same time. There are other caveats with replication so ensure to research them along with how to deal with corruption and repair before considering this setup for a live application. Also be sure to be using the same version of MySQL on both servers – this may not always be necessary, however unless you are very familiar with any changes between versions, not doing so could spell disaster.