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

9.2 Sizing BIA
managed because only it retrieves the data for the selected columns, instead of
the traditional approach that gets the whole row.
Horizontal partitioning
The sizing of the BIA, covered in 9.2, “Sizing BIA” on page 197, is based on the
memory needs of the data to be managed by the BIA. Based on that is the
number of Blades that can manage that memory. For each Blade’s CPU, it
creates one partition. Each partition can hold one or a part of a
InfoCube/dimension data, depending on its size.
Smart compression
The BIA uses dictionary-based compression allowing it to reduce the size of the
data stored. It also allows it to manage all the data in memory. For this reason it
is important do correct sizing. If some paging is involved, the BIA performance is
going to be affected.
Massive parallel execution (MPE)
These techniques mentioned prepare the system for MPE. The queries and
loads can be partitioned on small independent parts and run on the different
partitions. Every step uses its own data on its own process and does not affect
any other step. The number of parallel sessions that can run on a BIA system is
one of the metrics of capacity sizing.
The purpose of the BIA is to improve the performance of queries on selected
InfoCubes. The customer has to evaluate the potential InfoCubes selected for
using BIA. SAP recommends not using the BIA for all InfoCubes. It should be
used for large InfoCubes (thousands of millions of rows) to speed up query
performance.
For the sizing process SAP Note 917803 explains how to calculate the memory
consumption using report ZZ_BIAMEMCONSUMPTION_BW3X.
Note: We recommend using the option P_DETAIL to get more precise results
for sizing.
To get the number of Blades needed for the BIA system you can use the
following algorithm:
Result of report x 2 (GB) / amount of memory on Blade (GB) = number of
Blades
Chapter 9. SAP BI Accelerator 197