Abstract

Unlike other database products, Db2 LUW© does not have all of its data in memory. This
is a big cost factor that makes Db2 LUW© very attractive for customers.
Although the demand for memory resources is moderate, Db2 LUW© is still able to run
peak load environments with excellent performance. The Db2 prefetching system is a
key technology that ensures that requested data is available in memory at the time it is
required.
Therefore, the understanding of the prefetching system, its configuration, monitoring,
and basic tuning options have become of increasing importance for database
administrators who need to ensure and improve the performance of a Db2 LUW©
database.
This document explains the Db2 LUW© prefetcher model and shows how you configure
and monitor asynchronous I/O, particularly for SQL query processing. It’s for
administrators of Db2 LUW© environments who have a fair knowledge of Db2 LUW©
administrative topics and tasks. The paper is based on the author’s experience with Db2
systems in SAP environments, but the information provided is expected to be helpful in
all environments running on Db2 LUW©.