Michael beat me to it, but I was going to suggest the OP get a RAID solution using it in Mirror mode. You would then have two or more duplicate copies of your music library. If one fails you pull the drive and replace it with a new one - the RAID system will automatically copy the remaining drive, creating a new duplicate. And so on. You can, of course, have more than one duplicate, but the RAID enclosure will become more expensive the more copies you have. They also tend to be more noisy than conventional drives (especially the cheaper models), requiring more cooling in larger housings. The other downfall is that this system does not maintain an off-site backup.
If you are simply looking for recommendations for external raw drives then Hitachi Ultra-Star's would be my pick. That said, any of them can fail, which is why back up is mandatory, IMO.