SCM BW vs. External BW
I have the following landscape: ECC, SCM, and External BW.
Which scenario is better for Demand Planning
1- Transfer the data (actual sales) from ECC to SCM BW
2- Transfer the data (actual sales) from ECC to External BW then to SCM BW
The best landscape depends upon the business requirements, the current landscape, plus any future landscape plans the client may have.
DP does not require any external BW; any required data CAN be extracted directly from ERP. However, from a business perspective, the client may already have, or may have plans to create at some point, a standalone enterprise level BW system, for reasons not related to DP.
If the client has no such plans, it makes little sense to go to the extra work of creating an additional BW system. However, you should present the choices to the client, and leave the final decision to him.
If the exact data you need already exists in the enterprise BW system, then for consistency sake you would want to investigate extracting from there. However, if you have to modify the existing BW to achieve your data requirements, then you should consult with the client for guidance. Any redesign of the existing enterprise BW may be out of scope.