Decommissioning
Actually switching the old system off, and proving nothing depended on it.
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This topic is part of the curriculum but has no questions, cards or glossary entries so far. The rest of Legacy Modernization may still cover what you are looking for.
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Legacy Modernization
General material on modernising existing systems.
Legacy Assessment
Understanding what a system does before deciding what to do with it.
No content yetThe Six Rs
Rehost, replatform, refactor, repurchase, retire, retain — per application.
No content yetRehosting
Lift and shift: fastest, cheapest, and capturing none of the benefits.
No content yetReplatforming
Targeted changes that capture operational wins without a rewrite.
No content yetRefactoring & Re-architecting
Changing structure incrementally while the system keeps running.
No content yetRebuild vs Re-architect
Why greenfield replacement fails, and the narrow cases where it does not.
Strangler Fig
Routing capabilities to new implementations behind a facade, one at a time.
Application Decomposition
Finding seams in a monolith, starting from the data.
No content yetDatabase Migration
Moving engines, versions and schemas without losing data or uptime.
No content yetData Migration Strategies
Backfill, dual-write, reconciliation and verification.
Zero-Downtime Migration
Expand, migrate, contract — and the contract phase that never happens.
No content yetParallel Run
Shadowing the old system to discover the rules nobody documented.
No content yetCutover Planning
Rehearsals, go/no-go criteria and a rollback that has been executed.
No content yetLegacy Integration Patterns
Anti-corruption layers, adapters and CDC against systems that cannot change.
No content yetMainframe Modernization
Batch windows, COBOL, and the risk profile of core banking systems.
No content yetMigration Risk
Bounding blast radius, staging by cohort, and honest readiness reporting.
No content yetModernisation Business Case
Pricing tail risk so deferred maintenance becomes fundable.
No content yetCoexistence Patterns
Running old and new together for years without corrupting either.
No content yet