Best Practices for SAP BI using DB2 9 for z/OS - IBM Redbooks

If transfer time takes the most elapsed time
For this condition, use transaction SM50 to determine whether there is resource
constraint. Check whether there are enough work processes, especially for
loading to PSA and data targets in parallel. Parallel processing can compete for
resources. Use the ST06 transaction to determine whether the bottleneck is in
CPU, memory, or network.
For parallel processing (load balancing) to multiple BW application servers,
synchronization among them is necessary because during large data load,
swapping of buffers of master data can occur on a BW application server.
Synchronization overhead of buffers among them can impact performance. You
can use ST05 to check the SQL trace for log table activities. If this problem
occurs, you can try to shut down other application servers and set
rdisp/bufrefmode=sendoff,exeauto during the load phase.
If upload (update) to a PSA takes the most elapsed time
Potential root causes for this condition could be I/O contention or the partitioning
configuration. I/O contention is a possible result of high volumes of insertion
during large data loads. Check for database I/O, disk layout, and striping
configurations to see whether you can improve it.
The partitioning configuration has an impact as well. If partitions are defined too
large, there may be no parallel database subprocesses used. If partitions are
defined too small, there may be too many parallel database subprocesses used.
Packet size and partition size can be done from transaction RSCUSTV6.
Note that in DB2 V8, the partition size defined in RSCUSTV6 will not influence
the number of partitions. SAP BW table makes use of the DB2 V8 partition
addition feature (for more details refer to 5.1.2, “Management of PSA” on
page 68).
The PSA table partition is automatically created for each data request in an
InfoPackage. If multiple data requests on the same Infopackage are loaded to
PSA, then the PSA table partition will have additional table partitions per the
number of loads of data requests. If the same data request load is repeated, a
new partition will be added.
Therefore, to influence parallelism, split large loads into multiple Infopackages
that each have only one data request. For more information refer to SAP note
number 485878 for “DB2/390: BW Partitioning the PSA tables”.
Transfer rules and update rules takes too long
For this condition you can use the simulation tool to debug the problem. For
example, in the RSMO detailed window, under Processing, select Data Package
Chapter 8. Query and Load performance 155