Database Reference
In-Depth Information
tions can be simplified in SAP HANA. In other cases, flawed data models or data flows
can be discarded and replaced with a better design.
This strategy also allows for a less stressful migration, since the old system remains oper-
ational with no disruptions while the new system is being implemented. In our experience,
the greenfield approach has been used in approximately one third of SAP BW on HANA
implementations.
1.1.2
Database migration strategy
In most cases, a significant investment has been made in the original system. The data
flows align with a layered scalable architecture (LSA) and the data models adhere to best
practice modeling guidelines. The queries and reports based on the original system deliver
the right results. Many years of requirements gathering, design, development, and testing
effort have been spent building the system, and there is no reason to discard or replace what
has already been built.
The best strategy for these types of systems is to migrate the database from the original
database to SAP HANA. Depending on the size of the system, there are two basic ap-
proaches which can be followed:
In-place migration
Downtime-minimized migration
For smaller databases, usually less than 10 TB, the in-place migration is the simplest, most
efficient, and most economical approach. Let's learn more about in-place migration.
In-place migration approach
An in-place migration is exactly what its name suggests: start with SAP BW on any data-
base and migrate it directly to SAP HANA.
In-place migrations require flexibility to schedule a system outage during which the data-
base will be migrated. When the migration is complete, the outage is over and the original
system is now running on SAP HANA. This approach is only recommended for smaller
systems because the migration takes longer for larger systems. Generally speaking, systems
less than 10 TB can be migrated over a three-day weekend.
