If you're worried for HDD failure, you may want to consider to use 2 similar HDDs with RAID-1 (mirroring). Even if the one fails, the data will remain to the other and you'll be able to replace the HDD and rebuild array.
I haven't the slightest bit of experience doing it on cPanel, but if this database is absolutely mission-critical and you're backing it up very often, it may make sense to look into replication (if, of course, you have a spare server somewhere):
It's generally talked about in the context of distributing the load across multiple servers, but it can be used for backup purposes, too. With the ability to do 'asynchronous' syncing, you could keep a Linux box in your basement or something and just sync the two every 30 minutes (or more!).
Again, I have no experience doing it on cPanel (and frankly, I doubt many people have?), but it seems like it could potentially be less cumbersome.