Mission-Critical Systems

When to Use

Classify criticality tiers (mission-critical, business-critical, important) with explicit impact criteria
Set availability, integrity, and continuity objectives (uptime, RTO/RPO, MTPD, data loss tolerance)
Map dependencies, failure domains, and blast radius for severe-impact services
Select architecture patterns—active-active, geo-redundancy, quorum, deterministic execution, fail-safe defaults
Define change and release governance—hold points, CAB tiers, emergency change, rollback criteria
Tailor monitoring, alerting, and escalation to criticality (SLOs alone are insufficient for Tier 0)
Align engineering with contractual SLAs, sector regulation, and continuity obligations (generic framing)
Produce criticality registers, architecture decision records, and governance briefs for leadership