Reliability vs Complexity
Mechanisms that add availability and add failure modes.
3 to work through
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advanced
A proposed architecture is more reliable in theory and substantially more complex to operate. How should that be evaluated?
2 min answer -
advanced
A team can improve availability by adding several components, each of which is itself a failure point. How should that be evaluated?
2 min answer -
advanced
Give an example of a reliability mechanism that made a system less reliable, and explain the mechanism.
2 min answer
3 terms in this topic
Complexity Budget
The idea that an organisation can operate only a bounded amount of complexity, so each resilience mechanism must justify its share.
conceptOperated Reliability
The availability a system actually achieves in the hands of the team running it - as distinct from the availability its topology implies.
conceptReliability versus Complexity
Mechanisms added for reliability introduce their own failure modes — so past a point, more machinery makes a system less reliable.
Neighbouring topics
Architecture Decision-Making
General material on making and recording architectural decisions.
Architecture Decision Records
One decision, its context, alternatives and consequences, kept immutable.
Reversibility
One-way and two-way doors, and buying optionality deliberately.
Build vs Buy
Differentiation, five-year TCO, and the exit cost of each option.
Monolith vs Microservices
A team-topology decision far more often than a technology one.
SQL vs NoSQL
Decided by access patterns and query flexibility, not by data volume.
Sync vs Async
Whether the caller's outcome depends on the callee's response.
Strong vs Eventual Consistency
A per-operation decision, resolved by what a stale read would cost.
Managed vs Self-Managed
Trading control and unit cost against operational attention.
Serverless vs Containers
Spiky and event-driven versus sustained throughput.
Single vs Multi-Region
Driven by RTO, RPO and residency rather than by ambition.
Centralised vs Distributed
Shared platform leverage against team autonomy.
Performance vs Cost
Buying latency, and knowing what the last millisecond is worth.
Security vs Usability
Varying control by the value of the action rather than uniformly.
Delivery vs Maintainability
Fast in the cheap places, careful in the expensive ones.
Deciding Under Uncertainty
Bounding the downside and buying information cheaply.
Trade-off Analysis Methods
ATAM, scenarios, and naming the points where qualities conflict.
Technology Selection
Evaluating options against drivers rather than against enthusiasm.
Decision Practice
Thresholds, review, supersession and keeping the log alive.