I do main data at home, external HD as backup offsite (I update maybe 1-2x a year otherwise it's turned off/unplugged), and any new files not on the backup are in cloud storage + local HD, separate from main data.
If either drive failed I'd just order a new one since the odds of both failing within a couple days would be low.
Have a Maxtor 250GB external from 2004, but it's been unplugged since 2008ish only being turned on and used maybe a dozen times since then