mirroring subversion servers

This might be outside the scope of this mailing list but any help would
be most appreciated.

We have be happily using Subversion for about a year now. The number of
engineers using our repository is growing very rapidly.

At this point, I really want to setup another server as a slave that
will take over if the main server (the master) fails.

I was reading about Heartbeat (http://linux-ha.org/index.html) and
figured something like this with SVN::Mirror might be a good idea.

Does anyone have experience with this (or any other) type of setup?

Thanks!

Sean