RAID protects against disk failure — deletion, ransomware and fat fingers replicate instantly.
Redundancy keeps the array serving through hardware faults. It faithfully mirrors every mistake, too. Different threat, different tool.
It is also not nothing. RAID genuinely removes the most common single cause of data loss, and for an array that is itself the backup target the distinction blurs. The rule warns against treating it as sufficient, not against valuing it.
Estimate with the rule, then check it against the calculator that models it properly.
Open RAID Calculator →RAID protects against disk failure — deletion, ransomware and fat fingers replicate instantly. Redundancy keeps the array serving through hardware faults.