EO Engineering Learning OS
PROJECT LADDER · P16
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CORE PROJECT · TARGET L4 · 7 days
P16

Disaster recovery

Prove the system can restore service and data within agreed business limits.

01 / CONCEPT MAP

Know what the parts mean.

Learn each concept deeply enough to recognize it, place it in the system and reason about normal and failed behavior.

01

Business impact

Define it · locate it · observe it · explain its failure mode.

02

RPO and RTO

Define it · locate it · observe it · explain its failure mode.

03

Backup

Define it · locate it · observe it · explain its failure mode.

04

Restore

Define it · locate it · observe it · explain its failure mode.

05

Regional failure

Define it · locate it · observe it · explain its failure mode.

06

Runbooks and drills

Define it · locate it · observe it · explain its failure mode.

02 / SYSTEM FLOW

Trace it end to end.

Failure declaration→containment→restore infrastructure→restore data→validate→resume

For every transition: identify input, output, identity, protocol, state, trust boundary, evidence and owner.

03 / GUIDED BUILD

Build, observe and explain.

Documentation and AI are allowed. The engineer must review every output and demonstrate the result from direct evidence.

  1. 01Set RPO/RTO
  2. 02Inventory dependencies
  3. 03Automate backups
  4. 04Restore in isolation
  5. 05Run timed recovery drill
  6. 06Record gaps and improve
04 / INCIDENT

Backups report success but the latest restore fails due to missing encryption-key access.

Required investigation

State impact → collect evidence → form competing hypotheses → test the cheapest discriminator → isolate root cause → contain → correct → verify.

Evidence pack

Timeline, relevant logs/metrics, failed assumptions, root cause, correction, verification and one prevention action.

AI ownership

AI may suggest causes and commands. The engineer must explain why each check is safe, what result is expected and how the result changes the hypothesis.

05 / DESIGN CHALLENGE

Defend the decision.

Choose backup/restore, pilot light, warm standby or multi-site based on business need and cost.

06 / VERIFY, SUBMIT & REVIEW

Submission evidence

Architecture review

  • Explain disaster recovery without relying on memorized commands.
  • Draw the flow and name what crosses every arrow.
  • Identify the most likely, highest-impact and hardest-to-detect failure.
  • Show the evidence that proves the solution works.
  • Defend one security, reliability and cost trade-off.

Definition of Done

  • Acceptance criteria pass
  • Flow is drawn and explained
  • Security implications considered
  • Logs/metrics checked
  • Failure is tested
  • AI output is understood
  • Runbook is reusable
  • Mentor review passes
07 / MENTOR GUIDE

Do not score memory. Score the engineer’s ability to form a model, collect evidence, make a safe change and defend the trade-off.

1 Cannot explain2 Understands with gaps3 Implements and troubleshoots4 Designs and reviews