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Line 1: {{for\|the type of disk partition\|Disk partitioning#Extended partition}} {{redirect\|LPAR\|the conference\|Logic for Programming, Artificial Intelligence and Reasoning }} {{Short description\|Subset of a computer's hardware resources, virtualized as a separate computer}} {{Lead too short\|date=September 2024}} A '''logical partition''' ('''LPAR''') is a subset of a computer's hardware resources, [[Platform virtualization\|virtualized]] as a separate computer. In effect, a physical machine can be partitioned into multiple logical partitions, each hosting a separate instance of an [[operating system]].<ref name="Singh">{{cite web \|url=http://www.redbooks.ibm.com/redpieces/pdfs/sg247803.pdf \|title=Security on the Mainframe \|date=2009-12-02 \|access-date=2010-04-06 \|first=Karan \|last=Singh \|url-status=dead \|archive-url=https://web.archive.org/web/20110617113238/http://www.redbooks.ibm.com/redpieces/pdfs/sg247803.pdf \|archive-date=2011-06-17 }}</ref> == History == {{section rewrite\|date=December 2024}} [[IBM]] developed the concept of [[hypervisor]]s ([[virtual machine]]s in [[IBM CP-40\|CP-40]] and [[CP-67]]) and in 1972 provided it for the [[IBM System/370\|S/370]] as [[VM (operating system)\|Virtual Machine Facility/370]].<ref>{{ ~~cite book \|url=http://www.vm.ibm.com/pubs/HCSF8A50.PDF \|title=z/VMbuilt on IBM Virtualization Technology General Information Version 4 Release 3.0~~ cite book \|url=http://www.vm.ibm.com/pubs/HCSF8A50.PDF \|title=z/VMbuilt on IBM Virtualization Technology General Information Version 4 Release 3.0 \|id=GC24-5991-04 \|date=2002-04-12 \|publisher=[[IBM]]}}</ref> IBM introduced the Start Interpretive Execution (SIE) instruction (designed specifically for the execution of virtual machines) in 1983 as part of [[IBM System/370-XA\|370-XA]] architecture on the [[IBM 3081]], as well as VM/XA versions of VM to exploit it. [[PR/SM]] is a type-1 Hypervisor based on the CP component of VM/XA that runs directly on the machine level and allocates system resources across LPARs to share physical resources. It is a standard feature on [[IBM System z]] only. An IBM POWER system uses PHYP (the POWER Hypervisor) to enable its LPAR functionalities for System p and System i since approximately 2000 in POWER4 systems. [[Amdahl Corporation]]'s Multiple Domain Facility (MDF) was introduced in 1982.<ref>{{cite journal \|last1=Doran \|first1=R.W. \|title=Amdahl multiple-___domain architecture \|journal=Computer \|date=October 1988 \|volume=21 \|issue=10 \|pages=20–28 \|doi=10.1109/2.7054 \|s2cid=1738798 \|url=http://www-ti.informatik.uni-tuebingen.de/~spruth/edumirror/xx067.pdf \|archive-url=https://web.archive.org/web/20170829211626/http://www-ti.informatik.uni-tuebingen.de/~spruth/edumirror/xx067.pdf \|archive-date=2017-08-29}}</ref> IBM introduced its functionally similar PR/SM in 1988, implemented on its [[ESA/370]] architecture released that year with the [[IBM 3090]] processors.<ref>{{cite web\|url=http://www.redbooks.ibm.com/redpapers/pdfs/redp5157.pdf\|title=IBM Z Functional Matrix\|author1=Frank Packheiser\|author2=Octavian Lascu\|author3=Bill White\|page=18\|publisher=[[IBM]]\|date=2018}}</ref> PR/SM (Processor Resource/System Manager) is a type-1 [[Hypervisor]] (a [[virtual machine]] monitor) that allows multiple logical partitions to share physical resources such as [[Central processing unit\|CPU]]s, memory, [[Channel I/O\|I/O channels]] and LAN interfaces; the LPARs can share I/O devices such as [[direct access storage device]]s (DASD). Initially, the operator could select either basic mode or logical partition mode. PR/SM is integrated with all [[IBM System z]] machines. Formally, LPAR designates the mode of operation or an individual logical partition, whereas PR/SM is the commercial designation of the feature.<ref name="Singh"/>{{rp\|83}} The terms ''PR/SM'' and ''LPAR'' are often used interchangeably in IBM Z, including in IBM documentation. Formally, LPAR designates the logical partitioning function and mode of operation, whereas PR/SM is the commercial designation of the feature.<ref name="Singh"/>{{rp\|83}} [[Amdahl Corporation]]'s Multiple Domain Facility (MDF) was introduced in 1982.<ref>{{cite journal \|last1=Doran \|first1=R.W. \|title=Amdahl multiple-___domain architecture \|journal=Computer \|date=October 1988 \|volume=21 \|issue=10 \|pages=20–28 \|doi=10.1109/2.7054 \|url=http://www-ti.informatik.uni-tuebingen.de/~spruth/edumirror/xx067.pdf \|archive-url=https://web.archive.org/web/20170829211626/http://www-ti.informatik.uni-tuebingen.de/~spruth/edumirror/xx067.pdf \|archive-date=2017-08-29}}</ref> IBM began marketing its functionally similar PR/SM in 1988, implemented on its [[ESA/390]] architecture released that year. MDF-based LPAR technology continued to be developed separately by Amdahl, and [[Hitachi Data Systems]] in part for their implementations of the new ESA/370 architecture, which featured the introduction of [[access registers]] that allowed use of multiple [[data space]]s addressable by a single [[address space]]. IBM subsequently continued its LPAR development with its 64-bit [[System z]] and [[IBM System i\|System i]] architectures. LPAR and PR/SM reconfigurations can be made without rebooting the computer, i.e., while some LPARs remain active. Reconfigurations can include changing channel path definitions and device definitions. IBM subsequently continued its LPAR development with its 64-bit [[System z]] architecture. LPAR and PR/SM reconfigurations can be made without rebooting the computer, i.e., while some LPARs remain active. Reconfigurations can include changing channel path definitions and device definitions. IBM introduced a related, simplified, optional feature called [[Dynamic Partition Manager]] (DPM) on its IBM z13 and first generation IBM LinuxONE machines. DPM provides Web-based user interfaces for many LPAR-related configuration and monitoring tasks. z/VM supports the z/Architecture [[HiperSockets]] function for high-speed [[TCP/IP]] communication among virtual machines and logical partitions (LPARs) within the same IBM zSeries server. This function uses an adaptation of the Queued-Direct Input/Output (QDIO) high-speed I/O protocol. IBM ~~later~~ introduced LPARs to their [[~~IBM~~PowerPC]]-based ~~i\|iSeries~~[[AS/400]] (later called iSeries) and [[IBM pSeries\|pSeries]] servers in 1999 and 2001, respectively,<ref>{{cite web \|url=http://www.ibm.com/developerworks/aix/library/au-aix-vioserver-v2/index.html \|title=POWER5 Virtualization: How to set up the Virtual I/O Server \|access-date=~~2008-09-~~September 25, 2008 \|date=~~2005-06-~~June 29, 2005 \|first=Nigel \|last=Griffiths \|website=[[IBM]] \|url-status=dead \|archive-url=https://web.archive.org/web/20080611131520/http://www.ibm.com/developerworks/aix/library/au-aix-vioserver-v2/index.html \|archive-date=2008-06-11 }}</ref> albeit with varying technical specifications. ~~Multiple operating~~Those systems ~~are~~use ~~compatible~~PHYP ~~with~~(the ~~LPARs,~~POWER ~~including~~Hypervisor) ~~[[z/OS]],~~to ~~[[z/VM]],~~enable ~~[[z/VSE]],~~their ~~[[z/TPF]],~~LPAR ~~[[AIX~~functionalities ~~operating~~since ~~system\|AIX]],~~approximately ~~[[Linux]],~~2000 ~~and~~in ~~[[IBM~~POWER4 ~~i]]~~systems. This Insupport continues in [[~~disk~~IBM ~~array\|storage~~Power ~~systems~~Systems]]~~, such as the IBM TotalStorage DS8000, LPARs allow for multiple virtual instances of a storage array to exist within a single physical array~~. Multiple operating systems are compatible with LPARs, including [[z/OS]], [[z/VM]], [[z/VSE]], and [[z/TPF]] on mainframes, [[AIX operating system\|AIX]] and [[IBM i]] on IBM Power Systems, and [[Linux]] on both. In first part of 2010 year, [[Fujitsu]] announced availability of its [[x86-64]] PRIMEQUEST line of servers,<ref>[http://www.fujitsu.com/global/news/pr/archives/month/2010/20100331-01.html Fujitsu Upgrades Lineup of PRIMEQUEST Mission-Critical Servers]</ref> which support LPARs. In [[disk array\|storage systems]], such as the IBM TotalStorage DS8000, LPARs allow for multiple virtual instances of a storage array to exist within a single physical array. In second part of 2011 year, [[Hitachi]] has announced availability of CB2000 and CB320 blade systems,<ref>{{cite journal \|url=http://www.hitachi.com/rev/archive/2012/__icsFiles/afieldfile/2012/03/26/r2012_02_104.pdf\|title=Logical Partitioning Feature of CB Series Xeon servers Suitable for Robust and Reliable Cloud \|archive-url=https://web.archive.org/web/20120914083641/http://www.hitachi.com/rev/archive/2012/__icsFiles/afieldfile/2012/03/26/r2012_02_104.pdf \|archive-date=2012-09-14 \|author1=Hitoshi Ueno \|author2=Shinichi Matsumura \|journal=Hitachi Review \|volume=61 \|date=2012 \|issue=2}}</ref> which support LPAR on [[x86-64]] hardware.▼ ▲In ~~second~~early ~~part~~2010 [[Fujitsu]] announced availability of ~~2011~~its ~~year~~[[x86-64]] PRIMEQUEST line of servers,<ref>{{citation \|url=http://www.fujitsu.com/global/news/pr/archives/month/2010/20100331-01.html \|title=Fujitsu Upgrades Lineup of PRIMEQUEST Mission-Critical Servers}}</ref> which support LPARs. In late 2011, [[Hitachi]] ~~has~~ announced availability of CB2000 and CB320 blade systems,<ref>{{~~cite journal~~citation \| url=http://www.hitachi.com/rev/archive/2012/__icsFiles/afieldfile/2012/03/26/r2012_02_104.pdf \| title=Logical Partitioning Feature of CB Series Xeon servers Suitable for Robust and Reliable Cloud \| archive-url=https://web.archive.org/web/20120914083641/http://www.hitachi.com/rev/archive/2012/__icsFiles/afieldfile/2012/03/26/r2012_02_104.pdf \| archive-date=2012-09-14 \|author1=Hitoshi Ueno \|author2=Shinichi Matsumura \| journal=Hitachi Review \|volume=61 \|date=2012 \|issue=2}}</ref> which support LPAR on [[x86-64]] hardware. ==Hardware partitioning==▼ ▲== Hardware partitioning == Logical partitioning divides hardware resources. Two LPARs may access [[memory (computers)\|memory]] from a common memory chip, provided that the ranges of addresses directly accessible to each do not overlap. It is possible for one partition to control memory managed by a second partition indirectly by communicating with a process on the partition with direct access, which acts as an intermediary. [[CPU]]s may be dedicated to a single LPAR or shared. While on Amdahl's MDF (Multiple Domain Facility) it was possible to configure an LPAR with both shared and dedicated CPUs, this is no longer possible with any mainframes currently in the market. On IBM mainframes, LPARs are managed by the [[PR/SM]] facility or a related, optional, simplified facility called Dynamic Partition Manager (DPM). All 64-bit IBM mainframes, except for the first generation 64-bit models (z900 and z800), operate exclusively in LPAR mode, even when there is only one partition on a machine. Multiple LPARs running z/OS can form a [[Sysplex]] or [[IBM Parallel Sysplex\|Parallel Sysplex]], whether on one machine or spread across multiple machines.<ref name="redbooks.ibm.com">{{cite web \|url=http://www.redbooks.ibm.com/abstracts/sg247803.html \|title=Security on the Mainframe \|date=2009-12-02 \|access-date=2010-01-14 \|first=Karan \|last=Singh}}</ref> On IBM [[IBM pSeries\|System p]] [[IBM Power Systems\|POWER hardware]], LPARs are managed by PHYP (the POWER [[Hypervisor#Unix and Linux servers\|Hypervisor]]).<ref>~~https~~{{cite web \|url=http://www.ibm.com/support/knowledgecenter/POWER6/iphb2/iphb2hypervisor.htm~~{{dead~~ ~~link~~\|~~fix~~title=IBM Knowledge Center \|website=www.ibm.com \|access-~~attempted~~date=~~yes~~22 May 2022 \|archive-url=https://web.archive.org/web/20161017172011/http://www.ibm.com/support/knowledgecenter/POWER6/iphb2/iphb2hypervisor.htm \|archive-date=~~September~~17 ~~2020~~October 2016 \|url-status=dead}}</ref> PHYP acts as a virtual switch between the LPARs and also handles the virtual [[SCSI]] traffic between LPARs. [[Micro-Partitioning]] supports 10 times as many LPARs as processors with fractional allocations. It was introduced with the [[POWER5]] processor. All IBM [[POWER5]], [[POWER6]], and successor systems may be partitioned. Note that a full system partition may be defined where all resources are consumed by a single partition. System P servers with PowerVM enabled allow LPARs with shared CPUs to delegate their unused cycles into the shared pool. Dedicated processors are not available for sharing. Unused cycles become available for other partitions and are governed by the parameters specified when the LPAR is defined. Changes to a running partition can be made dynamically up to the maximum value set, and down to the minimum value set in the active profile. The changing of resource allocations without restart of the logical partition is called [[Dynamic Logical Partitioning\|dynamic logical partitioning]]. IBM PowerVM is the licensed/purchased feature that enables the virtualization features on p4, 5, 6, 7, and subsequent series servers.<ref>{{cite web \|url=http://www-01.ibm.com/common/ssi/cgi-bin/ssialias?infotype=an&subtype=ca&appname=Demo&htmlfid=897/ENUS207-269 \|title=IBM System p Virtualization — The most complete virtualization offering for UNIX and Linux \|date=2007-11-06 \|access-date=2010-04-06 \|publisher=[[IBM]]}}</ref> Exploiting [[Intel vPro]] (i.e. [[Non-uniform memory access]]), there are also implementations of Logical Partitioning based on [[Xeon#Haswell-~~based_Xeon~~based Xeon\|Intel Xeon]] e.g. by [[Hitachi Data Systems]].<ref name="HDS">{{cite web \|url=https://www.hds.com/en-us/pdf/white-paper/hitachi-white-paper-high-performance-nested-virtualization-with-hitachi-lpar.pdf \|title=High-Performance Nested Virtualization With Hitachi Logical Partitioning Feature \|date=2014-09-01 \|access-date=2016-05-29 }}{{Dead link\|date=March 2020 \|bot=InternetArchiveBot \|fix-attempted=yes }}</ref> LPARs (with sufficient certification) safely allow combining multiple test, development, quality assurance, and production work on the same server, offering advantages such as lower costs, faster deployment, and more convenience. IBM mainframe LPARs are Common Criteria [[Evaluation Assurance Level#EAL5: Semiformally Designed and Tested\|EAL 5+]] certifiable, equivalent to physically unconnected servers, so they support the highest security requirements, including military use. Nearly all IBM mainframes run with multiple LPARs with the [[IBM System z9]] and [[IBM System z10]] supporting up to 60 LPARs and later models up to 85.<ref name="redbooks.ibm.com"/> == See also == [[VM (operating system)]] [[ {{anl\|Dynamic Logical Partitioning~~]] (DLPAR)~~}}▼ [[ {{anl\|Full virtualization]]}} ▲[[Dynamic Logical Partitioning]] (DLPAR) * {{anl\|HiperSocket}} [[Workload Partitions]] (WPAR)▼ {{anl\|Logical Domains}} [[HiperSocket]], [[Hypervisor]] [[ {{anl\|Platform virtualization~~\|Virtualization]]~~}} [[ {{anl\|PowerVM]]}} ~~[[Sun~~ ~~Microsystems~~{{anl\|~~Sun]] [[~~Solaris Containers]]}} ▲[[ {{anl\|Workload Partitions~~]] (WPAR)~~}} [[Sun Microsystems\|Sun]] [[Logical Domains\|LDOM]] ==References== ~~{{Reflist}}~~ {{refs}} ==External links==▼ [https://web.archive.org/web/20110617113238/http://www.redbooks.ibm.com/redpieces/pdfs/sg247803.pdf Security on the Mainframe], December 2009, by Karan Singh, Chapter 4. Virtualization, page 24 and page 83. ▲== External links == [https://www-01.ibm.com/servers/resourcelink/lib03030.nsf/web+search/0E6125F89F8B8EF6852572E6007E884D/$file/sa76-0098.pdf System i and System p: Logical Partitioning Guide]{{dead link\|date=January 2018 \|bot=InternetArchiveBot \|fix-attempted=yes }} [http://www-01.ibm.com/common/ssi/cgi-bin/ssialias?infotype=an&subtype=ca&appname=Demo&htmlfid=897/ENUS207-269 IBM System p Virtualization — The most complete virtualization offering for UNIX and Linux]▼ [https://web.archive.org/web/~~20120304165859~~20110617113238/http://www.~~hds~~redbooks.ibm.com/~~assets~~redpieces/~~pdf~~pdfs/~~hitachi-datasheet-compute-blade-logical-partitioning-lpar~~sg247803.pdf ~~Hitachi~~Security ~~Compute~~on ~~Blade~~the ~~LPARs~~Mainframe], December 2009, by Karan Singh, Chapter 4. Virtualization, page 24 and page 83. * [https://techknowledgedb.com/system-i-and-system-p/ System i and System p: Logical Partitioning Guide] [http://www.fujitsu.com/downloads/PRMPWR/wp-xpar.pdf Fujitsu XPARs (SPARC)] and [http://www.fujitsu.com/global/services/computing/server/primequest/technology/io-partitioning.html "Flexible I/O and Partitioning" (x86_64)]▼ ▲ [~~http~~https://www~~-01~~.ibm.com/~~common~~docs/~~ssi~~en/~~cgi-bin~~announcements/~~ssialias?infotype=an&subtype=ca&appname=Demo&htmlfid=897~~archive/ENUS207-269 IBM System p Virtualization — The most complete virtualization offering for UNIX and Linux] * [https://public.dhe.ibm.com/systems/power/docs/hw/p9/p9hat.pdf Power Systems Logical partitioning] * [https://web.archive.org/web/20120304165859/http://www.hds.com/assets/pdf/hitachi-datasheet-compute-blade-logical-partitioning-lpar.pdf Hitachi Compute Blade LPARs] ▲* [http://www.fujitsu.com/downloads/PRMPWR/wp-xpar.pdf Fujitsu XPARs (SPARC)] and [http://www.fujitsu.com/global/services/computing/server/primequest/technology/io-partitioning.html "Flexible I/O and Partitioning" (x86_64)] * [http://publib.boulder.ibm.com/infocenter/eserver/v1r2/index.jsp?topic=/eicaz/eicazzlpar.htm System z PR/SM] {{Virtualization products}} {{use American English\|date=September 2022}} ~~{{DEFAULTSORT:Lpar}}~~ {{use MDY dates\|date=September 2022}} [[Category:AS/400]] [[Category:Hardware partitioning]] [[Category:IBM mainframe technology]] [[Category:IBM storage software]] [[Category:Virtualization]] [[Category:Virtualization software]]