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

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In general, database administrators (DBAs) are not responsible <strong>for</strong> some of the<br />

processes discussed in this book, <strong>for</strong> example, analyzing and defining <strong>SAP</strong><br />

aggregates (which are summary tables optimized <strong>for</strong> specific queries). It is<br />

important, however, <strong>for</strong> DBAs to be aware of these activities, since aggregate<br />

analysis and definitions should generally be done be<strong>for</strong>e solving a problem,<br />

when the root problem is a lack of aggregates. Missing or improperly defined<br />

aggregates can cause increased CPU usage, excessive I/O activity, and<br />

increased <strong>DB2</strong> memory usage.<br />

Evaluation of query per<strong>for</strong>mance <strong>for</strong> <strong>SAP</strong> <strong>BI</strong> requires both <strong>SAP</strong> in<strong>for</strong>mation (such<br />

as query per<strong>for</strong>mance indicators RSDDSTAT, or aggregate valuation and<br />

definition in RSA1) and also <strong>DB2</strong> indicators (such as cached statement statistics,<br />

or <strong>using</strong> <strong>DB2</strong> EXPLAIN PLAN to analyze the access path used by <strong>DB2</strong>).<br />

Likewise, an <strong>SAP</strong> <strong>BI</strong> administrator may not be familiar with the technical issues<br />

of DB structure, SQL evaluation, and <strong>DB2</strong> parallelism capabilities. But if, after<br />

evaluating the data model and aggregates, there are still per<strong>for</strong>mance problems,<br />

the <strong>SAP</strong> <strong>BI</strong> administrator can work with the <strong>DB2</strong> DBA to evaluate the<br />

<strong>DB2</strong>-related changes to address per<strong>for</strong>mance problems. Not all problems can be<br />

solved with aggregates, and the <strong>BI</strong> administrator may need to turn over some<br />

problems to the <strong>DB2</strong> DBA.<br />

1.3 Why run <strong>SAP</strong> <strong>BI</strong> on <strong>IBM</strong> System z<br />

The z in System z signifies zero downtime. System z hardware is designed to<br />

meet the world’s most critical computing needs. Reliability characteristics such<br />

as dynamic CPU sparing, logical partitioning, error detection and correction, and<br />

hardware cryptography are built into the architecture.<br />

If the nonspecialist <strong>IBM</strong> system offers 99.99% availability, the result is only 53<br />

minutes of unplanned downtime per year. If the sysplex gives 99.999%<br />

availability, there is only 5 minutes per year of unplanned downtime.<br />

1.3.1 Value provided by System z, z/<strong>OS</strong>, and <strong>DB2</strong><br />

In this section we give an overview of the value provided by System z, z/<strong>OS</strong>, and<br />

<strong>DB2</strong>.<br />

One-stop shopping<br />

<strong>IBM</strong> provides a one-stop shop <strong>for</strong> all three components — hardware, operating<br />

system, and database.<br />

4 <strong>Best</strong> <strong>Practices</strong> <strong>for</strong> <strong>SAP</strong> <strong>BI</strong> <strong>using</strong> <strong>DB2</strong> 9 <strong>for</strong> z/<strong>OS</strong>

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