Logical partition (virtual computing platform)

LPAR ( Logical Partition ) is the division of an IBM mainframe computer ( mainframe) into multiple virtual systems. Each virtual system can be an instance of the same or different operating systems to run. The division is implemented by the Processor Resource / System Manager (PR / SM), which is a function LIC (LIC = Licensed Internal Code, a type BIOS of the mainframe ).

The system administrator can specify which resources ( CPUs, memory, etc. ) are to be allocated to a partition. In a System z Parallel Sysplex processor and I / O resources can be dynamically controlled by Workload Manager so that targets are met as possible.

The use of LPARs is an example of a server partitioning.

System z

Modern System z computer (eg z10 Enterprise Class) can manage up to 60 LPARs.

With the help of the operating system z / VM can on an IBM mainframe as many virtual machines are created if sufficient resources are available.

ZLinux operating modes

  • Native Mode: all available hardware resources are used
  • LPAR mode: Hardware resources are divided into "logical partitions "
  • VM mode: Hardware resources are " virtualized ", for example under the Hypervisorbetriebssystemen z / VM or KVM ( Kernel-based Virtual Machine)

The native mode is in the current System z machines are no longer available, because these systems can be operated only in LPAR mode.

PSeries / System p / Power Systems

Power4 -based computers can contain up to 32 logical partitions. The granularity of partitioning is a CPU, 256 MB RAM, I / O adapter in pSeries. With AIX version 5.2L the LPARs can be repartioniert dynamically (without reboot). Linux, AIX 5.1 and AIX 5.2 operating systems can be operated simultaneously in a pSeries computer in different LPARs. When Linux distributions are Novell SuSE Linux SLES 8 and 9 for PPC as well as Red Hat Advanced Server 3.0.

From POWER5 and AIX 5.3 LPARs can be operated with computationally less than a whole CPU. This so-called Micro Partitions ( or Shared Processor LPARs short SPLPARs ) need at least 0.1 CPU shares (Capacity Entitlement, short CE), which can be changed in increments of 1%. Thus, per CPU up to 10 LPARs conceivable.

There are two operating modes: capped / capped (hard limit on CEs ) and without caps / uncapped ( top open). Particularly elegant and easy-care are uncapped SPLPARs, since the CE allocation from the POWER Hypervisor ( PHYP ) is calculated every 10 ms new. LPARs that have little load, make their CEs to the pool to enable LPARs can be satisfied with high load.

Since AIX 6.1 and the new Power6 technology LPARs can be moved from one machine to another. This feature is called Live Partition Mobility. In addition to AIX are supported as another LPAR operating systems SuSE SLES 10 and 11 Server for PPC.

PCs & Servers

PCs and servers ( x86 ) not have permitted establishment of LPARs. First provider of this technology is HDS (Hitachi Data Systems ) with the Hitachi Compute Blade System CB500 or CB2000. Where up to 60 LPARS be created ..

Alternatively, you can most likely achieve a similar partitioning with Xen. Other existing software solutions for virtualizing computer systems are commercial products such as VMWare ESX. Free products are KVM, VirtualBox, Bochs, Virtual PC, QEMU and User Mode Linux.


  • Virtualization
  • Mainframe
  • IBM