Coexistence and decommissioning

No BW modernization happens in one weekend. For a period, often years, BW and its successors run side by side: BW in the private cloud edition, BW data products in Datasphere, new models built on SAP-managed data products, and SAC stories reading from all of them. Coexistence must be managed so users always know which number is official, and decommissioning must be planned so BW is switched off safely before 2030.

Rules for coexistence

• One official source per KPI at any time. The use case register says whether "margin by customer" is official in BW or in Datasphere, and since when.
• Parallel run before switch. The new model runs alongside BW for at least one full period close, reconciled every period.
• Label everything. Stories and workbooks show which source they use and whether it is official.
• Freeze changes on the old side. Once a use case is rebuilt, changes go into the new model only; BW changes need an exception.
• Keep loads healthy. BW extractions from CMP continue until the last dependent use case switches.

History and decommissioning

The hardest decommissioning question is history. Finance may need seven years of margin history; auditors may need specific periods; BW may hold the only copy of data from the ECC years before the conversion. Options include moving history into Datasphere (for example as BW data products or into the object store, which SAP describes as a store for large volumes rather than a cold-storage replacement), keeping a read-only BW until a cut-off date, or archiving with your retention tooling. Each needs a reconciliation of the moved history and a legal check of retention rules.

Coexistence is also a communication problem. Users need to know, for each report they use, where it lives now, when it moves, what changes in how they open it, and who to ask. Contoso publishes the use case register as a simple list in its intranet, sends a note to users two weeks before each switch, keeps the old BW workbook available read-only for one period after the switch, and adds a banner to it pointing to the new story. Training focuses on the differences users will notice, such as navigation and filter behavior, not on the tool in general.

Finally, decide what to keep from BW after it is gone. Contoso exports query and InfoProvider definitions, transformation code and the last regression baselines as documentation, because questions about historical figures (“how was 2025 margin calculated?”) continue for years. That archive is small, cheap and often the only answer an auditor or a new controller can get once the system is switched off.