Now accepting guest editorial from SAP, Oracle, Workday and ServiceNow practitioners.Pitch a guide
The Sign-Off Table

Lesson 1 of 5

What DMO does

9 min

Listen to this lesson

0:00 / 6:31

SAP S/4HANA runs only on SAP HANA. Many ECC systems, including Contoso's production system EP1, still run on another database type, which SAP calls anyDB. Moving such a system to SAP S/4HANA needs two things: a database migration and a software change. The Database Migration Option (DMO) of the Software Update Manager does both in one procedure, with one downtime. When SUM detects early in the run that the source database is not SAP HANA, it enables DMO for the conversion.

SAP describes standard DMO as an in-place procedure: the application server level stays where it is, SUM runs on the primary application server (PAS) host, and only the database changes. The SAP ID and the application server host are kept, which keeps the impact on the rest of the landscape small. The alternative, a classical heterogeneous system copy with the Software Provisioning Manager followed by a separate upgrade or conversion, needs two maintenance events and two rounds of testing; SAP recommends DMO when the target is SAP HANA and DMO is possible.

Why SAP recommends DMO when it is possible: one procedure and one downtime instead of two maintenance events and two rounds of testing.
The Sign-Off Table · thesignofftable.com/academy/sap-bas-302
  1. PrepareSUM starts on the PAS host; target SAP HANA database is set up (client, schema)
  2. Shadow on targetUptime: shadow repository is built on the target database
  3. Enter downtimeThe system's database connection switches to SAP HANA; the source is no longer changed
  4. Migrate application dataR3load pairs export from the source and import into SAP HANA, with data conversion
  5. Finalize updateTarget kernel used; remaining update and conversion phases complete
  6. Start on SAP HANAThe system runs on the target database
Standard DMO in six moves, based on SAP's DMO overview. The source database keeps running but stores no new data.
The Sign-Off Table · thesignofftable.com/academy/sap-bas-302

How the data moves

SUM migrates application data with R3load processes that run in pairs: one exports from the source database and one imports into SAP HANA. They work through buckets, which are work packages of tables or table parts. In standard DMO the pairs exchange data directly through memory (pipe mode), so no large dump files are written and no big export file share is needed. SUM also calculates table splitting itself, based on table sizes, so large tables are cut into pieces that can migrate in parallel. With SUM 2.0 SP 08 and higher, SAP states that the shadow repository is created on the target database for all migration scenarios.

One R3load pair in standard DMO: the exporter reads a bucket from the source and streams it through memory to the importer, so no dump files are written.
The Sign-Off Table · thesignofftable.com/academy/sap-bas-302
PAS hostSUM and its R3load pairs run here; the application server instance stays
Source database (anyDB)Read during migration; application data not modified; remains as fallback
Target database (SAP HANA)Shadow repository built in uptime; application data loaded and converted in downtime
In-place DMO: one application server, two databases during the run.
The Sign-Off Table · thesignofftable.com/academy/sap-bas-302

What DMO needs

  • The scenario planned in the Maintenance Planner, including target-release kernel files for the target database and the SAP HANA client.
  • All archives in the SUM download folder on the SUM host.
  • A migration key, requested and received in advance.
  • The target SAP HANA database installed and sized, with network bandwidth between source and target hosts (SAP's tuning guidance mentions 10 Gbit/s and no firewall in between).
  • Up-to-date database statistics on the source, because table splitting is calculated from them.
  • For SAP S/4HANA targets, a supported source operating system and database as listed in the Product Availability Matrix.

What would you do?

Early in Contoso's planning, a consultant proposes migrating EP1 to SAP HANA with a heterogeneous system copy in one weekend, then converting to SAP S/4HANA two months later. Grace asks Sam whether this is wise. What is the best answer?

Key points
  • DMO combines a software update or S/4HANA conversion with a database migration in one SUM run and one downtime.
  • Standard DMO is in place: SUM runs on the PAS host, and only the database changes.
  • R3load pairs migrate buckets in pipe mode; SUM calculates table splitting itself.
  • Prepare target kernels, the HANA client, the migration key, a sized target database and good network bandwidth.

Check your understanding · not graded

Lesson check

  1. 1. What does 'in place' mean for standard DMO?

  2. 2. What is R3load pipe mode?

  3. 3. Why should source database statistics be current before a DMO run?

  4. 4. Where is the shadow repository created in DMO with SUM 2.0 SP 08 and higher?