Evidence
What is compared, how it is compared, and what gets recorded.
Migration Assurance
This is the part of architecture that earns trust.
A migration is not real when the diagram changes. It is real when the team has enough evidence to believe the new path behaves well enough under load, quality, and operational stress.
What belongs here
Section titled “What belongs here”Gates
Which thresholds must be green before traffic moves.
Rollback
What triggers reversal and how quickly the system can recover.
A useful assurance loop
Section titled “A useful assurance loop”- Define the slice of traffic, data, or workflows being compared.
- Choose the validation mode: replay, shadow, dual-run, or controlled rollout.
- Set explicit quality, latency, cost, and operational thresholds.
- Move traffic only when the evidence is strong enough and the rollback path is ready.
Questions to keep asking
- Which metrics actually matter for this migration, and which are just interesting?
- How much mismatch is acceptable before confidence drops below the cutover threshold?
- Who can approve the move, and what evidence do they need to see?
- What does rollback look like in minutes, not in theory?