STEP 2.4: ENHANCE SYSTEM RETIREMENT POLICIES
Each Legacy Data Store will have a System Retirement Policy in place stating the minimum that must be done before the system is retired. You now also have the new system design. From the two you can work out the gaps where the new system design will not fulfil essential business rules for legacy data.
A warning here — it is not the responsibility of the data migration project to audit the new system design. New functionality will always differ from old in some way. That is for the Programme Experts to propose and resolve through their own mechanisms. What you have to consider is access to historical ...