RAID keeps a server running when a single drive fails. It does nothing to protect you from ransomware, an accidental "delete all," a bad firmware update, or a fire in the server room — because whatever RAID does to one disk, it does to all of them at once. If your only copy of business data lives on a RAID array, you don't have a backup; you have a single point of failure with extra steps.
RAID (Redundant Array of Independent Disks) spreads or mirrors data across multiple physical drives so the array survives one drive dying — RAID 1 and RAID 10 tolerate a drive loss with no downtime, RAID 5/6 tolerate one or two drive failures respectively. That's it. RAID has no concept of "yesterday's version" of a file — if data is corrupted, encrypted by ransomware, or deleted, RAID faithfully protects and serves that bad data across every mirrored/parity copy, because it doesn't know the difference between good data and bad data.
A common, budget-sane pattern: RAID 10 (or RAID 6) on the primary server for uptime and drive-failure tolerance, with scheduled backup jobs writing to a separate NAS unit on a different set of disks — ideally in a different rack, or at minimum on a different controller — plus a periodic off-site or cloud copy for disaster recovery. This is the same logic behind why enterprise deployments still budget for backup storage even on servers with the strongest RAID configuration.
Every server we sell ships with its RAID controller tested and battery/cache verified, and we stock dedicated NAS units for exactly this kind of separate-target backup setup. See our current tested inventory, backed by a 3-year warranty and AMC program.