Which method deploys a subset of the system rather than the whole system at once?

The method that deploys a subset of the system rather than the entire system at once is known as Phased Conversion. This approach allows for gradual implementation of the new system by introducing it in phases or sections. Each phase is tested and evaluated before proceeding to the next, which can help mitigate risks and allow users to adapt to the new system gradually.

Phased Conversion is particularly beneficial in complex systems where a full rollout could lead to significant disruptions if issues arise. By using this method, organizations can ensure that each part of the implementation is functioning properly, making it easier to identify and resolve problems in a controlled manner before moving on to the next phase. Additionally, this step-by-step approach can enhance user training and support, as users only need to adjust to one section of the system at a time.

In contrast, other methods such as Direct Conversion involve switching to the new system all at once, while Parallel Conversion runs both the old and new systems simultaneously, and Pilot Conversion implements the new system in a limited environment first. Each of these methods has its own advantages and challenges, but none specifically focus on the gradual deployment of subsets of the system like Phased Conversion does.