Dynamic reconfiguration: Basic building blocks for autonomic computing on IBM pSeries servers

A logical partition in an IBM pSeries symmetric multiprocessor (SMP) system is a subset of the hardware of the SMP that can host an operating system (OS) instance. Dynamic reconfiguration (DR) on these logically partitioned servers enables the movement of hardware resources (such as processors, memory, and I/O slots) from one logical partition to another without requiring reboots. This capability also enables an autonomic agent to monitor usage of the partitions and automatically move hardware resources to a needy OS instance nondisruptively. Today, as SMPs and nonuniform memory access (NUMA) systems become larger and larger, the ability to run several instances of an operating system(s) on a given hardware system, so that each OS instance plus its subsystems scale or perform well, has the advantage of an optimal aggregate performance, which can translate into cost savings for customers. Though static partitioning provides a solution to this overall performance optimization problem, DR enables an improved solution by providing the capability to dynamically move hardware resources to a needy OS instance in a timely fashion to match workload demands. Hence, DR capabilities serve as key building blocks for workload managers to provide selfoptimizing and self-configuring features. Besides dynamic resource balancing, DR also enables Dynamic Capacity Upgrade on Demand, and self-healing features such as Dynamic CPU Sparing, a winning solution for users in this age of rapid growth in Web servers on the Internet.