The 3-2-1 rule in practice
Keep three copies of business data, on two different kinds of storage, with one copy offsite. For a small office, that usually means the working data, a NAS on site that backs it up automatically, and a cloud or offsite copy of the NAS. Versioned backups let you restore files from before a mistake or a ransomware infection, not just the latest state.
Why NAS-rated drives
NAS drives such as WD Red Pro and Seagate IronWolf Pro are built for 24/7 operation in multi-drive enclosures, with vibration handling and firmware tuned for RAID, and the Pro models carry five-year warranties. Desktop drives and renewed enterprise drives cost less up front, but for the drives holding your business backups, a new NAS-rated drive with a full warranty is the safer choice. That is why this list only includes NAS drives of 8TB and up.
RAID is not a backup
RAID keeps a NAS running when a drive fails, but it copies deletions, corruption and ransomware to every drive instantly. Treat RAID as uptime protection and keep separate, versioned backups, including one that is offline or offsite.