ITPEC FE Morning October 2023 Question 56
Which of the following is the most appropriate characteristic of the “big bang” or all-at-once migration method that is one of the system migration methods?
Explanation
Problems during migration have a big impact — big bang switches everything to the new system at one moment, with no old system running as a fallback.
Migration methods differ in how old and new systems overlap:
- •Big bang (all at once): the whole old system is stopped and the whole new system starts at a single point in time
- •Parallel: both run side by side for a period, results are compared, then the old one is retired
- •Phased: the system is moved part by part, so old and new parts must work together for a while
Big bang is cheap and fast, but any failure hits the whole organisation at once and there is nothing to fall back on.
Answer (d)
Why not others:
- •(a) — extra operating cost from running both systems belongs to parallel migration
- •(b) — a bridge application linking old and new systems is needed in phased migration, where the two must coexist
- •(c) — old and new systems operating in parallel is parallel migration, the opposite of big bang
Key rule: Big bang trades low cost and short duration for high risk; parallel trades extra cost for a safe fallback; phased needs the systems to interoperate.
System Development Technology · AI-written, may contain errors
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