Efficient way to keep a backup HD

[Christopher Turner]

Hello,

I'm setting up a new machine that will need hard drive redundancy.  I'm
looking for the most efficient way to keep a second hard drive that i could
quickly use to return the machine to functionality(without a disparity in
data between the two) should the main one fail.

I've looked into rsync, rdump, and vinum but i'm uncertain of the most
applicable method for my situation.

I have two 40G hard drives.  I will be running database, www, and mail apps
on this machine.  I don't plan on using the second drive for anything but
backing up the first one and being able to use it as primary if the first
one fails.

Which application appears to be best for me?  Are there any other programs
that would suit me?

What would be a good way to initialize the second hard drive for mirroring?

Thanks!

-- 
Christopher Turner
christopher at contemplation.org