Upgrade from SCM 5.1 to SCM 7.0 EHP1

Hello Experts,

We are planning to upgrade our APO system from 5.1 to 7.0 (EHP1).

During the initial study we came to know that we need to deactivate the Demand planning area before upgrade the APO system.

Is this step is mandatory or optional?

If we don't deactivate a planning area during upgrade then what kind of issues we would face in future?

Your help is greatly appreciated.

Thanks in Advance.

Sujay Joshi