4.4 Cost Optimisation
Purpose
Section titled “Purpose”Cost Optimisation focuses on delivering the solution at the lowest reasonable cost while meeting all other quality requirements. It covers cost-aware design decisions, cost analysis, and ongoing cost management practices. Evaluate this quality attribute across all architectural views documented in Section 3.
4.4.1 Cost Influence & Analysis
Section titled “4.4.1 Cost Influence & Analysis”Design Cost Decisions
Section titled “Design Cost Decisions”How do the design decisions in hosting, compute, networking, data storage, and resiliency demonstrate cost-effectiveness?
| Posture | Selected | Detail | |---------|----------|--------| | Design decisions chosen for specific reasons other than cost | [ ] | [describe why] | | Most cost-effective options intentionally not selected | [ ] | [describe why and the tradeoffs] | | Most cost-effective options selected | [ ] | [describe the analysis] |
Cost Analysis
Section titled “Cost Analysis”Has cost analysis or modelling been performed to inform design decisions?
- [ ] No - A cost analysis has not been performed
- [ ] Yes - [describe the analysis approach, tools used (e.g., cloud pricing calculators, TCO models), and key findings]
4.4.2 Cost Implications
Section titled “4.4.2 Cost Implications”Has the design been constrained in ways that do not fully meet requirements because of cost?
- [ ] No - The design fully meets requirements; cost has not impacted the design
- [ ] Yes - [describe how and why cost constrained the design, and the impact]
4.4.3 FinOps Practices
Section titled “4.4.3 FinOps Practices”Document ongoing cost management practices:
| Practice | Implementation | |----------|---------------| | Cost monitoring | [dashboards, alerts, tools] | | Cost allocation | [tagging strategy, cost centres] | | Reserved capacity | [reserved instances, savings plans, committed use] | | Rightsizing reviews | [process and frequency for reviewing resource utilisation] | | Waste elimination | [process for identifying and removing unused resources] | | Budget governance | [budget alerts, approval thresholds] |
Guidance
Consider documenting:
- Expected monthly/annual run cost breakdown by component
- Cost comparison of alternatives considered
- Cost optimisation opportunities identified but deferred
- Triggers that would necessitate cost re-evaluation (e.g., scale events, contract renewals)
Scoring Guidance
| Score | What This Looks Like | |:-----:|---------------------| | 1 | Cost acknowledged as a concern but no analysis performed | | 3 | Cost analysis completed, monitoring enabled, tagging strategy in place | | 5 | All of the above plus reserved capacity assessed, right-sizing evidenced, cost model linked to cloud calculator, FinOps practices documented |