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name: backup-disaster-recovery-and-data-migration description: Plan, implement, test, and audit backups, disaster recovery, VPS or cloud migrations, restore drills, RPO/RTO targets, data consistency, and retirement of old resources. Use before any recovery, replacement, resize, cross-cloud move, backup policy change, or destructive cleanup.

Backup, Disaster Recovery, and Data Migration

A backup is not a recovery capability until a restore has met its declared RPO, RTO, integrity, and security requirements. Keep backup, migration, cutover, and cleanup as independently auditable phases.

Reference basis: NIST contingency planning guidance for coordinated recovery of systems, operations, and data after disruption.

1. Establish the recovery contract

For every critical service, define owner, data classes, dependency order, RPO, RTO, backup frequency, retention, encryption/key owner, restore destination, validation query, and last successful drill. Use the business impact to prioritize recovery; do not use a single generic target for all services.

2. Back up for restoration

• Capture application-consistent data: database logical/physical backup, object data, configuration, identity/Vault recovery material, and artifact/digest references as appropriate.
• Verify backup completion, encryption, retention, immutability/access separation, and restore readability. A successful upload alone is not verification.
• Never store backup credentials, unseal keys, or database passwords in Git, CI secrets, artifacts, or local temporary files. Use OIDC → Vault short-lived access.
• Track backup provenance: source instance ID, volume/data size, application version, timestamp, checksum or integrity result, and restore compatibility.

3. Drill restores

Run scheduled restores into an isolated target. Measure actual RPO/RTO, validate schema/application health and representative data, then destroy the drill target only after recording results. Treat a failed or overdue drill as a recovery risk, not an administrative task.

4. Migration and resize decision

1. Preflight source/target capacity, architecture, OS/runtime compatibility, required ports, DNS, and dependency order.
2. For in-place upgrades, take a verified rollback point and validate the provider supports the requested operation.
3. For downgrades, cross-cloud moves, or target disks smaller than the source, use application-level backup and restore. Do not assume a volume snapshot can restore to a smaller disk.
4. Create and verify the replacement; adopt it into Terraform state; regenerate CMDB/inventory; deploy configuration; run data and service health checks.
5. Cut traffic/DNS only through an explicit, reversible decision. Retain the source during an observation window, then enumerate and explicitly approve its deletion.

5. Recovery execution

Use a written runbook with preconditions, exact backup identifier, target scope, ordered dependencies, validation, rollback/abort point, and communication owner. Do not overwrite a healthy source or clear initialization state merely because a key file or local marker is missing; stop and make a recovery decision with evidence.

Record every migration or restore with source/target IDs, chosen backup, planned and actual RPO/RTO, validation evidence, DNS/cutover time, and old-resource cleanup approval.