"My own cloud"

I think I have seen this topic before, but I didn't get it on the results.

I want to put my web server on a "fail-safe" mode. This is, is my primary server does down, a backup server will be online.

The approach is like this:

1. Set the DNS servers to have to A records with different TTL (is this possible?), so if the primary goes down, it will redirect to the backup
2. rsync the html directory every hour/half hour/whatever.
3. Make the main server's MySQL to "master" and the backup as "slave" and make replications.

Any suggestion? Thank you! =)