Immutable Backup

An immutable backup is designed to resist modification or deletion after it is written, often by using storage controls, object-lock features or another write-once retention mechanism. This matters during ransomware and administrator-account compromise: an attacker who can delete ordinary backups may have more difficulty changing correctly configured immutable copies. Immutability depends on the actual storage and permission model, not the name of a backup plan.

A sound recovery strategy still needs multiple copies, separate access controls, monitoring and tested restoration. Retention periods must be chosen carefully: data may remain unavailable for deletion until the protection expires, which has privacy and cost implications. Operators should confirm who can change retention settings, whether privileged users have exceptions, and how the protection survives account or provider failures.

Immutability does not guarantee that a copy contains clean data or that a restoration can finish quickly. A compromised system can sometimes write already-corrupted files to a protected backup. Combine immutable copies with backup verification, incident planning and documented recovery objectives. The term is different from simply storing backups off-site or keeping multiple historical versions; those measures can help resilience but may still permit deletion.