[CentOS] Warm standby server with rsync

I'm trying to mirror a live server onto a slave server of identical
hardware. Theory being that when the master server blows up I can change the
IP of the slave, restore the db's, restart a few processes and make everyone
happy again.

What is the best way of doing this? Can you literally rsync / (with the
exception of perhaps /proc and /tmp) and create an identical copy of the
master? Is there a better way to achieve this?

I've looked at using cluster suite but I don't think the instant(ish) and
automatic failover justifies the cost of the shared storage.

TIA,

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Nick B