Duplicate server!

I have been looking around this forum for a while now, can't seem to find the answer i am looking for.

Basically I have a web server running (one server with mail / dns / web) on cpanel/whm. I just got another server and looking to backup my first server. I am looking to backup the first server in a way that if server 1 fail - server 2 can take over (it is called a "fail over" i believe). Server 2 already has its own cpanel/whm installed.

Now rsync seems to be the best solution for that. First step i need to be able to sync all important files for the two servers to be an exact duplicate.

Syncing files in /home dir will sync webpages.
But what are the other folders that i should sync ??? (for accounts/ resellers/packages/dbs/quotas/....all).

Once i get my sync working and server 2 is a real copy of server 1 - then the second step will be for server 2 to take over when server 1 is down. But for now i am just looking at completely syncing server 1.

Any help would be greatly appreciated!!!