There are many different ways to perform data migration depending on client requirements and i2i best practices, external system availability, migration complexity and the actual data volume. No matter what approach is chosen, at the beginning of data migration process, the source databases must be examined to make an initial evaluation of the scope of the data cleansing and data conversion activity required. This examination of the source database will provide the basis for the data migration strategy.
There are number of data migration cutover approaches that can be considered depending on situation. These are;
- Big-Bang Migration: All data from existing systems are migrated over to chosen target platform at once during a predetermined migration cutover duration. For instance, a long weekend can be chosen for the migration activity and at the end of this period, the old systems will stop its operation and the new system will be in production. Even though, there are number of risks involved with this approach, looking at the benefits and simplicity, it is always a good candidate.
- Horizontal Migration: According to this strategy, part of data to be migrated (such as subset of entire customer base) is migrated to chosen system. For instance, we might decide that only prepaid or postpaid subscribers are moved to target system. Or, only part of the subscribers (within a customer number range) is migrated to target platform.
- Vertical Migration: According to this approach, only some functionality will exist in the target system. For instance, for a first step, new system can be used only for trouble ticketing purposes or only for invoicing of Corporate customers.