How to optimize DMO performance to reduce downtime
To reduce the migration duration of a standard DMO run, we recommend to consider the following features of Software Update Manager:
- Use the Benchmarking option of SUM
- Provide the duration file of a DMO run to the next run
- Use the Migration Repetition Option of SUM to immediate repeat the migration part
- Consider using downtime-optimized DMO (uptime migration)
As a rule of thumb, it should be possible for a standard setup to reach a migration rate of around 300 GB/hour.
Note that SUM proposes default values for the R3load processes (for uptime and downtime migration) which do NOT reflect the system data (like number of CPUs). You should always adapt those number of processes. It is not uncommon to have several hundred R3load processes, it only depends on the performance of the Application Server Instance host on which SUM is running.
1. Use the Benchmarking option of SUM
Before you start a complete DMO test run, we highly recommend using the benchmarking tool to evaluate the migration rate for your system, to find the optimal number of R3load processes and to optimize the table splitting.
- Benchmark Migration | SAP Help Portal
2. Provide the duration file of a DMO run to the next run
A benchmarking run as well as a full DMO run will measure and note the real migration times per table. These information are stored in the duration file. Copy the duration file from one run to the download folder of the next run. SUM will then consider the table migration time (instead of the table size) for calculation of table split which is more appropriate.
3. Use the Migration Repetition Option of SUM to immediate repeat the migration part
For a complete DMO run, the migration will only happen after all the preparation steps are done. You may reset the DMO run to repeat the migration with adapted parameters, but it will take a while until the DMO run reaches the migration part. Instead, for a test run, you can tell SUM to directly repeat the migration after it finishes. Benefit is not only that you will directly have the next migration run, but SUM will also automatically use the duration files from the previous migration run for the new split calculation.
4. Consider using downtime-optimized DMO (uptime migration)
If you follow all those hints and still need to further reduce the migration downtime part, you may consider to use downtime-optimized DMO (also known as uptime migration). It is available for a migration targeting SAP HANA database.