Memory hook: Know the owner, keep only what you need, test restoration.
Must remember
Classify data by business impact and obligations, then label and protect it consistently. Owners decide use/classification; custodians implement handling. Controllers determine processing purposes while processors act under applicable instructions; exact legal duties depend on jurisdiction and contract.
The lifecycle runs through collection/creation, use, sharing, storage, retention and disposal. Minimize collection, restrict purpose and access, discover misplaced sensitive data and track copies. Data residency describes where data is stored; sovereignty/jurisdiction concerns which laws may apply. Encryption does not automatically resolve every cross-border obligation.
Choose disposal by medium and sensitivity: clear, purge or physically destroy using an approved sanitization method. A quick format or ordinary file deletion may leave recoverable data. Track disposal and verify sanitization; retain evidence when required. Legal holds can override routine deletion.
RPO measures tolerable lost data in time; RTO measures target restoration time. A business impact analysis prioritizes services and dependencies. High availability handles component failures; backups recover prior data; disaster recovery restores technology; business continuity sustains critical business operations.
Full backups simplify restoration but copy more data. Incremental backups copy changes since the preceding backup and may require a chain; differential backups copy changes since the full backup. Offline/isolated or suitably immutable copies resist attacks on live systems. Replication can also replicate corruption and deletion.
Hot, warm and cold recovery sites trade readiness for cost. Test restoration, application consistency, key availability, access, DNS and dependent services. Redundant power, UPS/generators, geographic diversity and people/process continuity address different failure modes.
Choose under exam pressure
| Requirement | Choice and reason |
|---|---|
| Recover yesterday’s deleted records | A tested point-in-time/backup capability, not only replication. |
| Minimal data loss after disaster | A replication/backup frequency consistent with the RPO. |
| Retire sensitive storage | Approved sanitization with verification and records. |
Traps
- Replication is not a substitute for independent recovery history.
- A backup without usable decryption keys may be worthless.
Active recall
1. RPO versus RTO?
RPO is tolerated data loss in time; RTO is target service-restoration time.
2. Which backup needs the last full plus latest differential?
A differential-backup restoration.
3. Why test a restore rather than only check job success?
A successful copy does not prove recoverability, consistency or timely restoration.
4. What suspends routine deletion for relevant evidence?
A legal hold through the authorized legal process.
5. Does deleting a file sanitize its physical storage?
Not necessarily; use the approved method for that medium and sensitivity.