LEARN. PRACTICE. GROW.Concept and mechanism
A migration must control who writes, to which destination, and from which point onward. Once new storage receives business writes, returning to the old copy can lose or diverge that state. Define cutover, reconciliation, and reversal criteria before the change. Encryption also adds dependencies: filesystem permissions do not replace authorization to use the key in the recovery context. In EBS, KMS key validation can be asynchronous, so an initially accepted response does not guarantee final resource state. Confirm the effective outcome and prepare required destination access with the appropriate owners before declaring the migration ready.
Guided application
For decommissioning, identify volumes, snapshots, references, and agreed retention. Do not invent legal periods or decide solely from resource age. Because EBS snapshots can share blocks, deleting half the snapshots does not guarantee halving cost. Estimate savings from storage actually released and preserve points still required. During RUN handover, provide mapping, owners, alerts, headroom, key dependencies, and a validated recovery procedure with functional criteria. In a fictional project, having a backup and contact list does not demonstrate autonomy. Record evidence of what was validated and limitations still open before closing the project. Keep unresolved dependencies visible to the responsible teams.
Rollback after new writes requires addressing data state as well as switching destination.
Common pitfalls
Initial response as final state; encryption as authorization; age as deletion; snapshot count as cost.
Related topics: Interfaces and dependencies · Capacity and growth · Performance and measurement
Close with demonstrated recovery, retention decisions, and clear operational responsibilities.
Reference: EBS encryption and KMS dependencies · DR Storage 2026-09; selected Linux and AWS storage behavior