Migration strategy
On this page 9 topics
Overview
Topics
- Cutover
- coexistence
- rollback
- data migration
Learn first
4 h of practice (estimate)
Learning outcomes
- Choose a cutover approach (big bang, phased by capability, phased by store or region, parallel run) and justify it.
- Design coexistence between old and new systems during migration.
- Plan data migration: mapping, cleansing, trial loads, validation, and final load.
- Define rollback plans and go/no-go criteria for each cutover.
Lessons
Lab and exercises
Lab
ARC-037-LAB1 · Larkspur migration plan
Outcomes: 1–4 · Time: ~4 h
- Compare cutover approaches for the web shop and the 120 stores; choose and justify.
- Design coexistence: master per data set per phase, routing, synchronization, end date.
- Write the data migration plan: mapping, cleansing, trial loads, validation, final load, delta.
- Write go/no-go criteria and a runbook with a rollback and decision owner for every step.
- Defend the plan to a role-played program director.
Acceptance: every cutover step has a rollback and a decision owner.
Exercises (case-based; six exercises)
| ID | Outcome | Task |
|---|---|---|
| ARC-037-EX01 | 1 | Compare big bang, phased by capability, phased by store, and parallel run for Larkspur given a November peak; recommend one. |
| ARC-037-EX02 | 1 | The sponsor wants everything live in one weekend to save cost. Write the architect's response with risk trade-offs. |
| ARC-037-EX03 | 2 | During the phased move, both the old shop and the new platform can edit customer addresses. Decide the master per phase and conflict rules. |
| ARC-037-EX04 | 3 | Draft the data migration plan for 2.4 million customers and 9 million orders, including validation checks. |
| ARC-037-EX05 | 4 | Write go/no-go criteria for the first store wave with owners. |
| ARC-037-EX06 | 4 | A rollback plan says "restore the old system from backup". Review it and fix it for data written after cutover. |
Show solutions
- EX01 Phased by store for the stores, phased by capability for web (catalog, then checkout), avoiding November; big bang rejected for risk; parallel run only for financial postings where reconciliation is cheap.
- EX02 Cost saved by big bang is small against the revenue-at-risk and rollback difficulty; propose compressed phases with a pilot and a clear rollback; the sponsor decides with the risk visible.
- EX03 One master per phase (for example the old shop until the account capability moves, then the platform); sync with timestamps; conflicts resolved by master wins; no dual editing, or block edits for migrating accounts.
- EX04 Mapping sheet; cleansing of duplicates; trial loads timed; checks: record counts, order totals per month against finance, orphan checks, random sample review; dress rehearsal; delta load; sign-off by data owner.
- EX05 Test results passed, migration validation within thresholds, staff trained, support staffed, monitoring live, rollback rehearsed; each with owner and evidence; decision by the program director.
- EX06 Restore alone loses new orders. Add: capture new-system orders in an export during the window, replay into the old system or finance, define the last safe rollback point and who decides, and rehearse.
Workplace evidence: a migration or cutover you planned and executed.
Quiz
Outcomes: O1 cutover approaches · O2 coexistence · O3 data migration · O4 rollback and go/no-go.
A self-check for you: nothing is graded, saved or sent anywhere. Choose an answer, then check it. You can try again as often as you like.
Practical part
Migration plan defense of the lab plan plus exercises ARC-037-EX01 to EX06. Pass: quiz at least 8/10, at least five of six exercises correct, and a lab where every cutover step has a rollback and a decision owner.
Common mistakes
One untested final data load; no coexistence plan; rollback that ignores data written after cutover.
Assessment
Migration plan defense.
Workplace evidence
A migration or cutover you planned and executed.
Career relevance
Most enterprise solutions replace something that is already running.