From my reading I need a synchronise master - master. so both servers
need to be hot. Such that the web servers are unaware of which server
the are communicating with, so should one pgsql server go down there
would be no interruption to the web servers.
I have used Rubyrep for such scenario in the past but that was for a small database so it didn't give me much trouble.
Shoaib Mir
http://shoaibmir.wordpress.com/