Reliability and Resilience
Keep EO services dependable through failures, spikes, and external disruptions.
What Reliability Covers
Reliability defines availability targets, failure handling, data restoration, observability, and readiness practices for sustained EO operations.
Why Reliability Matters
Mission users depend on timely, complete data. Unreliable services break workflows, reduce trust, and increase operational risk.
What Good Looks Like
Mature platforms design for redundancy, high availability, failover, and degraded service behaviour, backed by tested recovery and clear incident communication.
Minimum Requirements
- Defined uptime targets, SLIs/SLOs, and recovery objectives.
- Backup validation and tested restore procedures.
- Central monitoring, alerting, and on-call incident response.
- Regional failover and dependency outage plans.
- Regular drills for technical and communication readiness.
Availability and Service Levels
Uptime Targets
Set explicit uptime commitments by service tier.
SLIs and SLOs
Track availability, latency, correctness, completeness, and timeliness.
Error Budgets
Use error budgets to balance reliability and delivery speed.
Degraded Modes
Define safe degraded modes when dependencies fail.
Failure Modes and Recovery
Transient Failures
Use bounded retries and circuit breakers.
Dependency Outages
Isolate dependency failures and degrade gracefully.
Queue Backlogs
Monitor backlog growth with load-shedding policies.
Processing Failure Recovery
Support targeted reprocessing and checkpoint resumes.
Regional Failover
Exercise failover paths and data replication validity.
Data Protection and Restore
Treat backups and restore tests as first-class reliability controls, not infrequent compliance tasks.
Monitoring and Observability
Metrics
Capture service, workflow, and customer-impact metrics.
Logs
Centralize structured logs with retention and searchability.
Traces
Trace cross-service flows for bottleneck and failure analysis.
Alert Thresholds
Set severity-based thresholds tied to action playbooks.
Incident Visibility
Provide internal and customer-facing incident status views.
Testing and Operational Readiness
Run game days, dependency-risk reviews, and data timeliness/completeness checks to validate readiness.
Reliability Decisions
Decide target SLOs, active-active vs active-passive failover, and degradation priorities for critical workflows.
Metrics and Health Signals
- SLO attainment and error budget burn rate.
- MTTD/MTTR and incident recurrence rate.
- Backup restore success and objective compliance.
- Data completeness and freshness at delivery time.
- Customer incident communication timeliness.
Anti-Patterns
- Operating without measurable SLOs.
- No rehearsed recovery drills.
- Alert noise without prioritization.
- Treating observability as optional.
Implementation Checklist
- Is ownership clear?
- Are minimum controls defined?
- Are failure modes addressed?
- Are measurable health signals defined?
- Are anti-patterns named?
- Are dependencies on other domains explicit?
- Is there at least one EO-specific implementation example?
- Is there a practical implementation checklist?
Example EO Patterns
- Regional outage triggers failover with catalog read-only mode and delayed bulk processing.
- Critical alerting products prioritized while non-critical derivations queue during incidents.
- Monthly restore drills validate catalog/index recovery and customer download continuity.