I needed a way to get the code base of the sites (Mostly Drupal 7, a few wordpress, and custom coded sites), upload images and other asorted media in sync between the two servers. I looked at the couple common utilities, I've used RSync in the past to maintain backups on other servers, but it has limitations on two way sync on multiple live servers. Enter Unison, it does exactly what the name implies, unifies multiple copies of the same set of files into 2 (or more) identical copies.
About a week ago I started seeing some intermittent issues with my primary webserver, hosting most of my personal/professional sites, along with a few of my long standing clients websites and decided it was time to rethink my infrastructure scheme. I sat down and gave some thought as to what I wanted, needed and expected.
My shortlist of wants/needs: