Choosing a Migration Approach

Objectives

After completing this lesson, you will be able to:

  • Explain the main migration approaches

Paths to SAP BW/4HANA

There are two main approaches when moving from SAP BW to SAP BW/4HANA.

Watch the following video to get an overview of the different paths to SAP BW/4HANA.

Let's recap on the key migration approaches:

1. In-Place Conversion (Full System Conversion):

  • Target group: Customers who want to change their current SAP BW system into an SAP BW/4HANA system and who are already on an up-to-date release (preferable 7.5 powered by SAP HANA).
  • In-place conversion means the customer keeps the existing BW system and transfers it to SAP BW/4HANA (keeping the system ID (SID) same).
  • Approach without re-implementation; there is no disruption for existing business processes.
  • SAP provides tool support for all tasks: database migration (SUM-DMO or SWPM), ABAP release upgrade (SUM), and BW application conversion to SAP BW/4HANA (BW/4HANA Transfer Cockpit).
  • Release requirements: SAP BW 7.5 SP05 powered by HANA, but recommendation is a current SP level.
  • Generally available since March 2018.

2a. New Installation (Standard Greenfield Approach):

  • Target group: SAP customers or net new customers.
  • New installation of SAP BW/4HANA, for example, for customers setting a new greenfield SAP S/4HANA environment and in this project they also start from scratch with SAP BW/4HANA.
  • Build a system from scratch with a new data model and load only relevant data from existing source systems.
  • Re-engineering and process simplification based on modern data warehouse architecture.

2b. Shell Conversion (Accelerated Greenfield Approach):

  • Target group: SAP Business Warehouse customers or net new customers.

  • For customers who want a fresh start, SAP offers an option to transport certain objects (metadata of data models) from the existing SAP BW system to a newly installed SAP BW/4HANA system. These objects are converted into SAP BW/4HANA-supported objects during import into the SAP BW/4HANA system (for example, InfoCube –> ADSO).

  • Neither master data nor transaction data are transferred. The data has to be re-loaded from the original sources or from the original BW system.

  • The technical solution is similar to remote conversion but without data transfer.

  • Release requirements for original SAP BW system: SAP BW 7.x (regardless of which database).

  • Generally available from March 2018.

2c. Remote Conversion:

  • Target group: Customers who want to change their current SAP BW system into an SAP BW/4HANA system and who are on an older release level and not on SAP HANA.

  • Remote conversion means the customer builds up a new SAP BW/4HANA system (new SID) and transfers BW applications (meta data) and data (master data, transactional data) from the original SAP BW system.

  • Opportunity to pick and choose only future-proof data flows to build a clean, new SAP BW/4HANA environment.

  • Convert BW objects into the newly installed SAP BW/4HANA system. Multiple persistent BW objects like InfoCubes, classic DataStore objects, and optionally PSAs are replaced by advanced DataStore objects; MultiProviders and InfoSets become CompositeProviders.

  • No database migration or BW application upgrade required.

  • Release requirements for original SAP BW system: SAP BW 7.3 (regardless of which database).

  • General availability from April 2019.

3. Landscape Transformation:

  • Target group: Customers who want to consolidate their SAP BW landscape (multiple production systems) or carve out selected data models or flows into a global, new SAP BW/4HANA system. These customers run multiple SAP BW, SAP BW on SAP HANA systems, or hybrid cases.

  • Customer-specific conversion project required with guidance of SAP and SAP's tools for this scenario (service offering from SAP's Data Management & Landscape Transformation group).

  • Stay with current data warehouse landscape and move gradually to SAP BW/4HANA innovations.

  • Harmonized data models and shared master data through consolidation.

  • Carve out of single entities of the company to SAP BW/4HANA and leverage process simplification.

The best source for more details about all these conversion paths is the Conversion Guide on the SAP Help portal for SAP BW/4HANA http://help.sap.com/bw4hana.

The In-Place Conversion

Overview of the Process of an In-Place Conversion

In-Place conversion approach is especially suited for SAP BW systems, which are running on SAP HANA database already and upgrading them to the up-to-date release level of BW 7.50 is a suitable option.

SAP BW/4HANA Starter Add-On

The SAP BW/4HANA Starter Add-on is an SAP NetWeaver add-on that is required for an in-place conversion to SAP BW/4HANA. It provides relevant customizing enhancements to manage the conversion process, offers access to the conversion tools, and manages the conversion process.

Note
  • The technical name of the software component for the SAP BW/4HANA Starter Add-on is BW/4HANA.
  • The technical name of the software component for SAP BW/4HANA it self is DW4CORE.
  • Authorizations must be granted on the basis of the new authorization object S_RS_B4H.
  • Existing BW Add-ons might prevent its installation.

For additional detail please refer to following sources:

  • SAP note 2246699: SAP BW/4HANA Starter Add-on - Prerequisites and Installation
  • SAP note 2189708: SAP BW/4HANA Add-On Handling and Usage

System Modes

The in-place conversion process is managed by setting the SAP BW system to different modes:

  1. BW Mode:
    • A system in BW mode operates the same way as an SAP BW system without the SAP BW/4HANA Starter Add-On.

    • SAP recommends reverting to BW mode only in exceptional cases.

  2. Compatibility Mode:
    • After installation of the SAP BW/4HANA Starter Add-on, the system is initially in Compatibility Mode.

    • Unsupported (classic) Object types, processes, and user interfaces in existing scenarios are still tolerated in this mode, but cannot be created using user interfaces or BAdIs.

      They only can be imported from BI Content or from another SAP BW system.

    • All objects can be changed. However, prior approval is required to be able to export (transport) unsupported object types. This approval is attained by registering the object in an allowlist (report RS_B4HANA_WHITELIST_MAINTAIN).

    • The SAP BEx tools can still be used. For more information, see SAP note 2399578.

  3. B4H Mode:
    • No new objects with unsupported object types can be created at all (neither via interfaces or BAdIs, nor via BI Content transfer or import).

    • The SAP BEx tools cannot be used anymore.

    • Registering objects in the allow list of above is not relevant any more, as there are no unsupported objects in B4H mode.

    • Virtual InfoProviders for SAP Business Planning and Consolidation (SAP BPC) are still allowed.

  4. Ready for Conversion Mode:
    • This mode is used to perform the technical system conversion.

    • All system-wide cleanup operations have been successfully completed.

    • The system is fully prepared to start the conversion of the software components (for example, SAP_BW –> DW4CORE).

Execute Scope Transfer the In-Place Conversion

As shown in the figure above, the scenario-wise conversion for the unsupported objects is executed within the compatibility mode. The conversion tools are accessed in the SAP BW/4HANA Transfer Cockpit by the Execute Scope Transfer function in the Realization section.

The conversion tools are accessed in the SAP BW/4HANA Transfer Cockpit by the Execute Scope Transfer function in the Realization section. The associated task list enables you to select data flows or parts of them and transfer them in place into SAP BW/4HANA-compliant objects. The rough procedure of an in-place conversion is as follows:

  1. Scope selection: Define conversion objects based on MultiProvider, InfoCube, DataSource, Process Chain etc.
  2. Check for all dependent objects.
  3. PSA check: Either delete PSA (load all requests to target first) or create a field-based ADSO to replace the service provided by the PSA in the past. For more guidance see SAP note 2949412 (When is an ADSO as replacement for a PSA required and when not?) .
  4. Preparation of classic InfoProvider. For example, activation of all data.
  5. If SAP DataSources are included: Ensure proper transfer to ODP
  6. Locking phase on.
  7. Save data: Rename tables, as the original object and its tables will be deleted.
  8. Save metadata: Generate new BW objects using the original one as template.
  9. Retrieve data: Transfer all data to the new data model.
  10. Transfer all requests into new request management.
  11. Locking phase off.

The Shell Conversion

The shell conversion can be seen as an accelerator for pure greenfield approaches.

The key properties of a shell conversion are the following:

  • Future-proof BW applications of the existing BW system are transferred to the receiving SAP BW/4HANA without data (metadata only, that is, the BW data model).
  • During import, the object types are checked and converted into the SAP BW/4HANA successor object types.
  • During this transfer it is possible to specify new technical names for DSOs, InfoCubes and MultiProviders (see SAP note 2911800: SAP BW/4 Shell conversion - changing of object names).
  • The data, however, has to be reloaded from the original source or initially from the legacy SAP BW system (via ODP_BW).
  • One advantage of the shell conversion: low requirement for the release of the existing SAP BW system which can be SAP BW 7.0 on any data base.

There is a dedicated task list to execute a shell conversion. This task list is available in the SAP BW/4HANA Transfer Cockpit, which provides the Execute Scope Transfer function in the Realisation section of it.

The Remote Conversion

In contrast to the shell conversion, the remote conversion also transfers the data.

When comparing the in-place conversion with the remote conversion, the major difference is that in the remote conversion, the new SAP BW/4HANA system is set up on a blank new system (new system ID (SID)).

The key properties of a remote conversion are the following:

  • Future-proof BW applications of the existing BW system are transferred to the receiving SAP BW/4HANA with data.
  • During import, the object types are checked and converted into the SAP BW/4HANA successor object types.
  • Technical names cannot be changed.
  • The release requirements for the sending system are higher than within the shell conversion:

    • SAP BW 7.30: SP10 or higher
    • SAP BW 7.31: SP10 or higher
    • SAP BW 7.4: SP09 or higher
    • SAP BW 7.5: SP02 or higher
  • The receiving SAP BW/4HANA system must be on release 1.0 SP04 at least, but the more up-to-date the better (see SAP note 2513088 for more details).
  • The remote conversion functionality is part of SAP Landscape Transformation (SLT, DMIS add-on). The SAP BW/4HANA license includes this component's usage for remote conversion purposes.

After the metadata is transferred to the new SAP BW/4HANA environment and converted there into the new BW objects, all related master data and transactional data is also transferred based on cluster tables that reside both in the sender and the receiving system. During import, the data request information is retrieved and migrated into the new request management of SAP BW/4HANA.

There is a dedicated process monitor to execute a remote conversion. This monitor is available in the SAP BW/4HANA Transfer Cockpit which provides the Execute Scope Transfer function in the Realisation section of it.

Note
For additional details, please refer to following sources:

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