Look OP, hard drives will last a LOT of hours working a 24/7 365 duty cycle for 5 plus years. A lot of the better drives have more than one safety feature. Notebooks actually stop spinning and go to sleep if that is what you want. Some PARK the heads off the platters, other do all three, park the head, dump the buffer, and spin down for transport. The head won't hit the platters, while bumping the drive around.
As far a backup, the best is not another hard drive, it is not a tape drive, it would be a non magnetic drive, like a CDR, why? Magnetic fields won't wipe you stuff, FOREVER. Vinyl, CD and music rolls for the old players
will survive. All my music files are backed up on CDRs. I have 3 or 4 Memory card backups and an external HD too. You have to be careful with certain valve amps and speakers being close to your computer HDs. A lot of stereo speakers aren't shielded. BIG magnets, and hard drives don't mix...CDRs could give a hoot, ay?
Regards