We can use advanced migration techniques and use the additional infrastructure available to reduce the downtime and make system available to end users very fast.
Below are the few techniques which we need to consider for reducing the downtime:
1. We should do the package splitting, as more the number of packages more we can use R3load processes to execute these packages and reduce the downtime
2. We can perform table splitting so that one table can be split into large number of packages and can be processed via multiple R3load processes
3. We can use Distribution Monitor if we have sufficient numebr of resources (Additional App servers) to perform the maigration which we reduce the overall downtime
4. You can consider the option of using parallel Export and Import provided your Target Database is ready
Points to be noted before launching the Distribution Monitor:
1. You should use Java 1.6
2. You can use only Net variant while using the Distribution Monitor, FTP Variant is not supported yet by Distribution Monitor
3. You should have additional hardware resources
4. The Distribution Monitor does not support system copies of releases lower than SAP_BASIS 6.20.
5. The Distribution Monitor only perform the export and import for ABAP based system for Java system you can use SAPINST to perform export and import
Tools in the Distribution Monitor Package
Distribution Monitor is delivered with following tools :
- Distribution Monitor
- Package Splitter
- Time Analyzer
How to use the Migration Monitor:
To use the Migration monitor there are a few requirements which we need to consider in a customer landscape
1. We should have sufficient resources available (additional application servers)
2. We should have resources on Database servers and we should increase the oracle sessions as per requirement and resources availabel on DB server
3. We should have sufficient space on source database to increase the temp table spce to accomodate the parallel run of R3load processes. Ususally as per SAP recommendations we should have PSAPTEMP (or TEMP) table space as 20% of used DB, say your DB size is of 1 TB then you should try to increase TEMP table space to 200 GB
4. Please ensure that you use the sufficient R3load processes, as a thumb rule SAP suggests to use 1 to 3 R3load processes for Export per CPU and 1 to 4 R3load processes for import per CPU, so before starting the export and import you should know the hardware capacity to proceed.
5. You need to set the DB environment setting in the profile so that you can connect to source and target DB respectively.
6. It is strongly recommended to use R3load data files (<host>.dataDirs) and R3load control files (<host>.exportInstallDir, <host>.importInstallDir) only on local file systems. NFS-mounted file systems is not recommended by SAP as it fails on high parallel load.
7. On each host: set commDir in distribution_monitor_cmd.properties
8. Do not modify the template files
9. On the host where you want to run the preparation step: enter the options in distribution_monitor_cmd.properties file (and further options if you like)
10. Run the preparation step: distribution_monitor –p
11. After running the preparation mode for the first time it is recommended to save results of R3ldctl, R3szchk, PkgSplit and (optional) R3ta step and set the corresponding skip options in distribution_monitor_cmd.properties. This enables repeating parts of the preparation without repeating unnecessary steps
12. After changes to table structures R3ldctl and R3zchk have to be repeated
13. If export and import run on separate databases Prepare the target database .Start export and import on each host in parallel , else if export and import run on same database. Start export on each host. After all exports have finished drop source database. Prepare the target database .Start the import on each host
14. During export and import you can monitor the state with the display mode (distribution_monitor –d)