Dear Faheem,

This is possible using keepalived. (this is to switch to another server when one becomes unavailable)

Then create a script (using bash or any other programming language you are familiar with) which checks the database on the master server and when it changes copy contents to other server when available. The only problem is, when you are changing stuff and then the server becomes unavailable, because that work cannot be saved.

There are some solutions which work with a kind of local buffer and then when the external server comes up again it copies everything to that server and continues work online, sadly I can't name any. Maybe somebody else?

If you want more information, just contact me!