RAID

Redundant Array of Inexpensive Drives (as named by the inventor) or Redundant Array of Independent Disks (a name which later developed within the computing industry) — is a technology that employs the simultaneous use of two or more hard disk drives to achieve greater levels of performance, reliability, and/or larger data volume sizes.

RAID comes in many flavors but the consumer in general uses raid 1, mirroring.
One disk is an exact copy of the other so if one fails you still have all of your data on the other drive.
This is an excellent way to protect you against loosing your music collection but it won’t protects you against dropping the unit (kids, cats, dogs, drunk), water, fire, theft.
Another option is remote replication. You have one unit in the basement, one in your study or even better in the home of a relative and you synchronize the units over the internet.