I am implementing a fresh BW system (BW/4HANA) which will bring the finance data from S/4HANA. I am in the process of estimating the size of the system so that BW system can be allocated the required space in terms of GB. I roughly know the number of line items S/4HANA system will generate on the yearly basis lets say about a billion. We need to have BW to stage data worth of 2 years. I would appreciate if someone can let me know how to estimate the size of BW system i.e. how much memory BW system will need to handle this amount of data.