Immutable backups: The last line of defence for true resilience

Digital attacks are increasingly targeting the security level itself. Ransomware, misconfigurations and insider activities specifically target backups because the ability to restore data is central to an organisation's resilience. If retention periods are shortened or backups are deleted, the last chance to resume stable operations after an attack is lost.

Immutable backups counteract this development, as they protect recovery points from changes throughout the entire retention period. However, this protection is only effective if it is embedded in a well-designed overall architecture.

Immutable backups are based on storage technologies that reliably prevent changes. These include WORM (Write Once, Read Many) storage, object storage with fixed retention periods and legally binding locks, as well as backup repositories that enforce write-once properties on the application side. The central idea is that even privileged accesses have no possibility of manipulation. Locks can only be removed via clearly regulated, multi-level approvals. It is often assumed that snapshots are already backups. However, since they are linked to primary systems, they do not offer independent security.

Unchangeable backups create a reliable basis for operational and regulatory requirements. They secure recovery points even in complex incident situations and enable transparent documentation. Two key figures are decisive here: the Recovery Point Objective (RPO) and the Recovery Time Objective (RTO). The RPO describes the maximum tolerable period of data loss, while the RTO defines the maximum acceptable time to recovery. The resilience of both values is only ensured by practised, verifiable processes. When technical measures are linked to clear governance processes, the result is a protection system that limits attacks and delivers traceable results in audits.

The introduction of immutable backups affects both technical and organisational levels. Retention periods must be integrated into capacity, cost and lifecycle planning. Misconceptions about the equivalence of snapshots or the supposed automaticity of complete security through immutability can exacerbate risks. Organisations therefore benefit from clear responsibilities, documented approvals and regularly practised recovery processes, as these factors make a decisive contribution to actual effectiveness. With increasing automation and faster attacks, the importance of tested, immutable backups will continue to grow.