Changeover Techniques

- Parallel changeover requires that both old and new systems operate fully for a specified period. When users, management and the IT group are satisfied that the new system operates correctly, the old system is retired. This approach entails very low risk. If the new system does not work correctly, the organization can revert to the old system as a backup.

- Abrupt changeover occurs when users are converted from the old to the new system immediately upon its operational availability. This approach is usually least expensive but involves high risk of data loss and system failure. With this approach, the organization cannot revert to the old system as a backup.

- Phased changeover involves modular implementation and simultaneous operation of discrete system components or modules. It is extremely complex to coordinate, particularly with regard to consistency of data across multiple systems or locations. However, this approach retains the possibility to revert to a previous state.