Good preparation is a key to success
Prior to commencing the procedure of data transfer to SAP HANA DB, attention should be paid to the minimum requirements that the SAP system must meet in order to be transferred and run on the SAP HANA database:
- the SAP system version compatibility for the SAP HANA database has been provided at the SAP NetWeaver 7.4 level for ERP systems, and for the data warehouse it is SAP BW 7.31,
- the SAP system for the HANA database must be in the code version: Unicode.
A standard, universal procedure of copying the SAP system to a new database, including SAP HANA DB, requires the data to be exported from the source database and then to be imported to the target database. Therefore, the requirements for the SAP system to be transferred to the HANA database must be met before the commencement of data copying, which additionally complicates and lengthens the whole process. For example, if your SAP ERP system is in a version lower than NetWeaver 7.4, then you need to upgrade your system to a new version in the first place, and then to carry out the process of data migration to SAP HANA, and thus to implement two independent technical projects.
DMO, i.e. how to simplify the migration procedure
DMO – Database Migration Option – is a solution implemented in SUM – Software Update Manager – a tool which greatly simplifies the entire procedure of migration to SAP HANA and allows the SAP system to be migrated within a single project while fulfilling all the requirements that the SAP system on the HANA database must meet.
The advantages of the DMO procedure are:
- Simplification of the SAP system migration procedure
The DMO procedure enables you to upgrade the SAP system to a new version required by the SAP HANA database, to convert the code page to Unicode, and to transfer – migrate data from the source database to the SAP HANA database in a single project step.
- Reduced system unavailability
Unavailability of applications to the end-user has been reduced to a minimum. The upgrade of the SAP system version, code page conversion and data migration require that each time the system be shut down, which means the unavailability of applications to end users. The DMO procedure performs these actions during the same phase of the project, and thus applications are unavailable only once.
- Reduced time of regression tests
The implementation of the SAP system update procedure, code page conversion, and database changes require that each time detailed regression tests be performed for all business processes that are mapped in the SAP system. The test phase is one of the most important project steps, and very often it requires end-user engagement. With DMO, it is sufficient to run one testing session, irrespective of whether only a copy of data to the HANA database has been made, the SAP system version has been updated or the Unicode conversion has been carried out.
- Using a standard and well-known tool
DMO has been implemented as one of the functionalities of SUM: Software Update Manager means using a well-known and useful interface and technology based on a proven and well-documented SAP tool.
- Preservation of the SAP environment landscape
The procedure of the SAP system migration to the HANA database used in DMO results in technical switching of the database for the application, which means that only the HANA server is a new element of the environment. The SAP application remains installed on the same host, its SID does not change either.
- Limiting the risk of data migration
Using the DMO tool when migrating data to the SAP HANA database significantly reduces the project risk, even if the upgrade and conversion to Unicode are made at the same time. The source database remains unchanged, as all activities during which the data is changed are carried out in the target SAP HANA database. The source database remains available at all times without changes, even during the SAP system version upgrade. This means that after switching the application to the HANA database, the withdrawal of changes does not require a backup of the source database to be retrieved. DMO will reconnect the SAP application to the source database and delete the data from the target SAP HANA database.
- Versatility of the tool
Copies of SAP applications to the SAP HANA database using Database Migration Option can be made also for older versions of the system. DMO allows you to perform data migration along with version upgrade and code page migration to Unicode even as of the SAP R/3 4.6C version.
Database Migration Option is equipped with a number of features that enable you to monitor the performance of the system where migration processes are running on an ongoing basis and, if necessary, to increase or decrease the number of concurrent copying processes, allowing you to optimally leverage the capabilities of the hardware environment.
DMO can be run in a test mode, during which only part of the data from the source database is migrated to SAP HANA, for example by setting a limit of 5% of all tables and 1% of the largest tables, and this process can be repeated for various configuration settings. The statistics collected during such test sessions allow you to optimize the operation of DMO with the correct copy of the entire database.
DMO saves statistical information about the migrated objects and allows them to be used with the next copy. This allows you to make a trial copy of the system to SAP HANA, and in production run – to use the information about copy times of each table. DMO will automatically set a queue of tables to be copied based on times rather than their size, which can significantly affect the entire run time.
The migrations of very large SAP ERP systems, which additionally do not allow for applications to be shut down, require the optimization of the copying process to minimize the phase of the database unavailability. DMO uses SLT – SAP Landscape Transformation Replication Server, a technology which makes a copy of large tables during the system availability phase, and the switching of applications from the source database to the target SAP HANA database is done faster – only deltas of changes in source tables are migrated.
The migration of the SAP BW data warehouse can be optimized with the SAP Delta Queue Cloning technology. This procedure involves running at the same time two copies of the source SAP BW system and on the basis of the target SAP HANA database while the data source is connected. When the copying and alignment of the contents of the target database are finished, the final switching at the BW data source level to the HANA database is done and the old data warehouse instance is disabled.