Immutable backup

An immutable backup is a recovery copy protected from alteration or deletion for a defined retention period, including by ordinary administrative actions. Immutability can reduce the risk that ransomware or a compromised account destroys every copy, but implementation varies by storage, credentials and retention controls. It does not guarantee that the captured data is complete, clean or restorable, and a misconfigured source may faithfully preserve unusable content. Design should separate duties, protect backup identities, define retention locks, monitor failures and preserve at least one independent path where appropriate. Capacity and legal retention also require planning because locked data may not be removable early. Recovery tests must select real workloads and verify integrity, dependencies and time. A successful backup job is evidence of copying, not proof of recoverability.