There are four types of installation
• Direct
• Parallel
• Pilot
• Phased
1. Direct changeover
The old system is stopped and the new system is started.
Direct changeover takes less time and effort and it starts immediately but whenever the new system starts there's no back-up and the old system can't be recovered.
2. Parallel running
The new system is started but the old system is kept running alongside. Data is input into both systems.
If new system fails, the old can run as a backup. Two systems run at the same time so we can see which one works correctly. However, it costs too much and also needs time.
3. Pilot running
The new system is piloted (trialed) in a small part of the business. Once it is running correctly then the new system is implemented across the organisation.
If the new system fails only the small part of the organisation suffers, but if the system fails there's no back-up.
4. Phased running
The new system is introduced in phases as parts of the old system are gradually replaced with the new system.
It allows people to get used to new system, but if the new part of the system fails, there's no back-up.