Dynamic logical partitioning

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Partitioning your system is similar to partitioning a hard disk drive. When you partition a hard disk drive, you divide a single physical hard disk drive so that the operating system recognizes it as a number of separate logical hard disk drives.

On each of these divisions, called partitions, you can install an operating system and use each partition as you would a separate physical system.

A logical partition (LPAR) is the division of a computer's processors, memory, and hardware resources into multiple environments so that each environment can be operated independently with its own operating system and applications. The number of logical partitions that can be created depends on the system. Typically, partitions are used for different purposes, such as database operation, client/server operations, Web server operations, test environments, and production environments. Each partition can communicate with the other partitions as if each partition were a separate machine.

Dynamic logical partitioning (DLPAR) provides the ability to logically attach and detach a managed system's resources to and from a logical partition's operating system without rebooting. Some of the features of DLPAR include:
  • The Capacity Upgrade on Demand (CUoD) feature of the IBM® System p, which allows customer to activate preinstalled but inactive processors as resource requirements change.
  • The Dynamic Processor Deallocation feature of the IBM Power servers, and on some SMP models. Dynamic Processor Deallocation enables a processor to be taken offline dynamically when an internal threshold of recoverable errors is exceeded. DLPAR enhances the Dynamic Processor Deallocation feature by allowing an inactive processor, if one exists, to be substituted for the processor that is suspected of being defective. This online switch does not affect applications or kernel extensions.
  • DLPAR enables cross-partition workload management, which is particularly important for server consolidation in that it can be used to manage system resources across partitions.

DLPAR requests are built from simple add and remove requests that are directed to logical partitions. The user can execute these commands as move requests at the Hardware Management Console (HMC), which manages all DLPAR operations. DLPAR operations are enabled by System p firmware and AIX®.