What’s the safest way to store 8 TB or more of important files?

Don’t replace a healthy drive on an arbitrary schedule just because it reaches a certain age. Check its health data, error counts, temperatures, and whether backups can be restored. Replace it when it shows warning signs, becomes unreliable, or when you want to retire an older drive as a precaution. More importantly, verify your backups regularly and do occasional test restores; a backup that has never been tested may not be usable when needed.

RAID can improve availability, but it is not a backup. RAID 0 provides no protection at all and makes failure more damaging. RAID 1, RAID 5, or RAID 6 can keep a system running after certain drive failures, but deleted or corrupted files are still replicated, and the whole array can be lost through other problems. If you use an enclosure or NAS, still maintain a separate backup.

For several terabytes of mostly archival files, a reputable NAS or enterprise-oriented HDD is usually the more economical primary storage choice. An SSD is quieter and faster, but speed does not equal better archival safety. Rather than putting the entire budget into premium storage or a very large game library, reserve enough for at least one independent backup and preferably an off-site copy.

Use the 3-2-1 rule: keep at least three copies, on two different kinds of storage, with one copy in another location. For example, the main copy could be on a large internal HDD, a second copy on a separate external drive that is normally disconnected, and a third copy in cloud storage or at another physical location. This protects against drive failure, accidental deletion, theft, fire, and ransomware.

There isn’t a drive that can guarantee your data will survive. A hard drive can fail suddenly, and an SSD can also fail or lose data if it sits unpowered for a very long time. Reliability ratings are useful for comparing products, but they don’t make a single drive a backup. The important files should exist in several independent copies.