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Database Migration Option (DMO)
DMO of Software Update Manager (SUM) in a nutshell
- SUM can not only update software components, but can also execute a database migration (for ABAP based systems)
- DMO (Database Migration Option) is the combination of software update with the database migration
- To only migrate the database (without software update), the approach "DMO without system update" can be used
- The standard DMO is an inplace-procedure, as it keeps the Application Server level unchanged, it only changes the database (host)
- In addition, DMO can be used for move scenarios in which a transition of the complete system to a different environment is possible:
"DMO with system move", and "DMOVE2S4" (specifically for the conversion to SAP S/4HANA) - DMO allows an easy reset of the procedure at any point in time
- DMO supports the migration to target database type SAP HANA DB, and (depending on scenario) to other database types as well
- To reduce downtime, the approach of downtime-optimized DMO (also called uptime migration) can be used,
it will migrate selected large application tables already in uptime, and will consider the potential changes by end users;
Downtime-optimized DMO can be combined with DMOVE2S4, but not with "DMO with system move" - SUM 1.1 (for ABAP target systems based on SAP BASIS 7.40 and lower) allows to execute a Unicode conversion as part of the migration
DMO Processing Overview
The processing sequence is based on the shadow system functionality of SUM: the SUM creates the shadow repository on the target database until downtime phase. Then once the downtime starts, the database connection of the SAP system is switched to the target database. After migration of the application data (including data conversion), the upgrade is finalized and the SAP system runs on the target database. The source database continues to run and the application data in it are not modified, so it remains a fallback (via the SUM RESET function) throughout the complete process.
Data Migration by R3load
SUM delivers its own R3load tool which is used for the migration of the application table content. SUM starts several R3load pairs that work on buckets (work packages) to export data from source database and import data into target database. As both R3loads of a pair are running on the same host, they can directly exchange data using the pipe mode of R3load (not true for "DMO with system move"). The advantage is fast processing, as no dump files are created and no compression of files is required.
Reducing downtime with uptime migration
With SUM 2.0, it is possible to further reduce the downtime of a migration by using the approach of "Uptime Migration", also known as "downtime-optimized DMO". See SAP Note 2547309 for details.