Migration Execution Must Become Predictable Before Cutover
Strategy defines what will move; execution proves that the team can move it repeatedly, within the available window and with acceptable quality.
Each migration cycle should improve extraction, transformation, loading, exception handling and reconciliation until the final process is rehearsed rather than improvised.
22.1 Create a Repeatable Migration Runbook
Document source extracts, sequencing, transformation jobs, load order, validation, exception handling and ownership.
Use the same runbook during rehearsals and refine it based on evidence.
22.2 Control Extracts and Versions
Identify the source snapshot, extraction timestamp and file or dataset version used in each cycle.
Without version control, reconciliation disputes can become arguments about different source populations.
22.3 Validate Before Loading
Check mandatory fields, formats, referential integrity, duplicates and mapping validity before sending records to the target.
Rejecting bad data early is usually cheaper than diagnosing downstream transaction failures.
22.4 Sequence Loads by Dependency
Load reference and master data before dependent transactions. Respect relationships between legal entities, accounts, products, resources, projects and opening balances.
Record restart points so failures do not require unnecessary full reruns.
22.5 Reconcile at Multiple Levels
Use record counts, control totals, financial balances, key-field sampling and business scenario validation.
A matched record count can still hide wrong values; a matched financial total can still hide misclassified records.
22.6 Manage Exceptions Transparently
Maintain an exception register with category, count, owner, resolution and acceptance status.
Do not silently exclude failed records to make completion percentages look better.
22.7 Measure Migration Performance
Track extraction duration, transform duration, load throughput, error rate and reconciliation time.
Use rehearsal timing to validate the final cutover window and infrastructure assumptions.
22.8 Secure Business Sign-Off
Business owners should approve reconciliation evidence for their domains according to agreed criteria.
Technical completion and business acceptance are separate milestones.
From the Delivery Floor
A rehearsal reported 99.8 percent load success and was initially declared complete. Reconciliation later found that a small number of rejected records represented a large share of open receivables value.
The team changed reporting to include both record and financial significance. Future migration decisions were based on business impact rather than percentage alone.
22.9 The Delivery Leader's View
Migration status should report completeness, quality, reconciliation and unresolved business impact. A green technical load can still conceal a red operational risk.
Chapter 22 Implementation Checklist
- Is there a controlled runbook?
- Are extract versions identifiable?
- Is pre-load validation performed?
- Are load dependencies sequenced?
- Are restart procedures known?
- Are multiple reconciliation methods used?
- Are exceptions visible and owned?
- Is migration timing measured?
- Does business sign-off follow agreed criteria?
- Has the final run been rehearsed end to end?
Key Takeaways
Repeatability is the goal of migration rehearsal.
Control the exact source population used in every cycle.
Reconciliation must prove values, not only counts.
Exception significance matters more than raw percentages.
Business owners approve data correctness.
Closing Thought
Cutover should be the final repetition of a proven migration process, not the first time the full process is attempted.