Database Reference
In-Depth Information
The individual systems within a system landscape will be migrated one by one, and there
is limited capability to turn back once you've started. In a three-system landscape with
a development, acceptance, and production system, each would be migrated in sequence.
Returning the landscape to the original database would require restoring each system from
backup, meaning any new development would be lost. Therefore, a development and trans-
port freeze is highly recommended until all systems are on the same database and SAP BW
version (in case an upgrade is planned with the migration).
For larger systems, those with limited flexibility to schedule long outages, or where on-
going projects or other development impact the ability to introduce a transport freeze, a
downtime-minimized approach provides the most risk mitigation and least impact to the
existing landscape.
Downtime-minimized migration approach
In the downtime-minimized approach, a database copy of the system to be migrated is re-
stored on interim hardware. It is the copy which is migrated to SAP HANA, thus minimiz-
ing the need for an outage in the original system.
To keep data loads in sync with the original system, all delta queues are cloned using the
SAP post-copy automation (PCA) tool, which is available with SAP Landscape Virtualiza-
tion Management (LVM). Sync points are set before the database copy so that data can be
extracted from the cloned delta queues after the migration. When the data loads are caught
up, users are then transitioned from the original system to the new system.
The downtime-minimized approach results in two parallel landscapes; the original land-
scape can only be decommissioned after all systems have been migrated to SAP HANA
and all users have been transitioned to the new systems.
As a result of the parallel landscape, the need for interim infrastructure, and the additional
steps required to copy the database and clone delta queues, this approach is the most ex-
pensive migration option. However, the costs are more than offset by the risk mitigation
and limited impact on development activities and productive operations in the original
landscape.
Regardless of which approach is selected, different tactics are used depending on what oth-
er activities need to be accomplished. In most migration scenarios, an upgrade of SAP BW
is one of those activities. Other scenarios may include a Unicode conversion or an extra-
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