There are different scenarios for Migration:
1. New Installation:
The simplest case is usually a new installation. For customers who have not used any SAP BW system so far, this may be an interesting approach because a new installation is less elaborate than a migration, which involves time-intensive preparatory and post-processing work. If you can imagine large data volumes before an SAP BW implementation and if reporting speed is one of your top priorities, it's worth relying on SAP HANA technology today. It is no longer recommended to implement a new SAP BW system in combination with Business Warehouse Accelerator (BWA; see the below “SAP BW on SAP HANA
vs. Business Warehouse Accelerator”).
BW on SAP HANA vs. Business Warehouse Accelerator:
SAP BW on SAP HANA and the Business Warehouse Accelerator (BWA) both accelerate the execution of BEx queries at runtime. However, the technical architecture of the two approaches differs considerably. When using BWA, you can deploy two storage technologies (relational database of the SAP W system and BWA) in parallel for data retention. In the case of SAP BW on SAP HANA, however, you can only use SAP HANA as the primary database system. In this case, all SAP BW data is retained in the main memory, and reporting is accelerated for all data. When you use BWA, in contrast, reporting can be accelerated only for specific data. To do so, you must transfer data of individual InfoProviders explicitly to BWA (indexing). In contrast to BWA, the speed of data load processes is also increased with SAP BW on SAP HANA. On one hand, this omits time-intensive steps in the process chains, for example, the generation of indices for InfoCubes. On the other hand, performanceintensive processes, such as activation of DSO requests, are run directly on the SAP HANA database. By deploying SAP HANA and the Planning Application Kit (PAK), you can also considerably speed up the execution of planning functions. Ultimately, the remodeling of InfoCubes in SAP BW on SAP HANA is also significantly easier thanks to the simplified data model.
2. Migration:
When you are performing an SAP BW on SAP HANA migration, the primary database of an SAP BW system is replaced by SAP HANA. It is irrelevant here whether the SAP BW system has run on Oracle, DB2, MS SQL Server, or MaxDB so far. For this reason, this is often referred to as a migration of AnyDB to SAP HANA. The previous database is no longer required after the migration is completed and can usually be switched off completely. All data, SAP BW objects, and data models are still available after migration. This is also referred to as a nondisruptive approach because the SAP BW system's operation can be continued without major interruptions. The BWA that is potentially used for performance optimization loses its right to exist in an SAP BW on
SAP HANA scenario. While BWA optimizes data of only selected Info-Providers for fast reporting, SAP HANA retains all data in the main memory and thus accelerates all reports.
2.1 Manual migration:
For an SAP BW system, the database and possibly BWA is replaced with SAP HANA within the scope of a migration. Experience has shown that
manual migration (also referred to as the classic migration method) is deployed most frequently. The involved tools have proven successful
when implementing a heterogeneous system copy (system migration including a database or operating system change). Several additional
tools and special reports are provided for SAP HANA that must be used before and after the actual migration phase.
2.2 DMO and PCA migration options:
An alternative to manual migration is to use the database migration option (DMO), frequently in combination with post copy automation (PCA). DMO allows you to run a system upgrade and a migration to SAP HANA in just one step. This can be particularly useful if the SAP BW system doesn't yet have the required version for implementing a migration The basic idea of PCA is to automate the numerous individual steps, particularly for post-processing an SAP BW on SAP
HANA migration. This is supposed to ensure, among other things, that all migration steps are executed completely and in the correct sequence.
Rapid Deployment Solutions:
RDS are provided optionally to accelerate the implementation of SAP solutions presents three RDS packages that are relevant for SAP BW on SAP HANA. For example, SAP provides the RDS package Rapid Database Migration of SAP BW to SAP HANA with which you can speed up an SAP BW on SAP HANA migration.
High-Level System Architecture Before and After SAP BW on SAP HANA Migration:
