I want to use MySQL replication over WAN for backup purpose.
What are the Best practice for ensuring data consistency, and without too much manual interruption?
This is how I would do it
I would set up simple MySQL replication over a VPN.
The replication process is quite simple, and you could use a utility like OpenVPN.
This is the simplest and easy way I can think of.
This is a tutorial to set up replication in Fedora 10 (the process is going to be pretty much the same) http://www.howtoforge.com/how-to-set-up-mysql-database-replication-on-fedora-10
Here's how to set up an OpenVPN http://openmaniak.com/openvpn.php
You can use a MySQL Replication Monitor to ensure the process is running as it should.
are you just looking for backups or an actual mysql server running elsewhere?
DKNuckles answer is right on the $money...
However -If it is just backups - a simple backup script (free) might work well for you
http://sourceforge.net/projects/automysqlbackup/ A great script from firstname.lastname@example.org which takes daily, weekly and monthly backups of your MySQL databases using mysqldump. Features - Backup mutiple databases - Single backup file or to a seperate file for each DB - Compress backup files - Backup remote servers - E-mail logs and much more...
keep in mind - RUNNING BACKUPS IS A GREAT IDEA :-) as issues such as mysql data loss from human error, programming error etc would replicate across the vpn / cluster as well