Dynamic Logical Partitioning (DLPAR), is the capability of a

logical partition A logical partition (LPAR) is a subset of a computer's hardware resources, 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 ...

(LPAR) to be reconfigured dynamically, without having to shut down the operating system that runs in the LPAR. DLPAR enables memory, CPU capacity, and I/O interfaces to be moved nondisruptively between LPARs within the same server. DLPAR has been supported by the operating systems

AIX Aix or AIX may refer to: Computing * AIX, a line of IBM computer operating systems *An Alternate Index, for a Virtual Storage Access Method Key Sequenced Data Set * Athens Internet Exchange, a European Internet exchange point Places Belgi ...

and

IBM i IBM i (the ''i'' standing for ''integrated'') is an operating system developed by IBM for IBM Power Systems. It was originally released in 1988 as OS/400, as the sole operating system of the IBM AS/400 line of systems. It was renamed to i5/OS in ...

on almost all POWER4 and follow-on POWER systems since then. The

Linux kernel The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ope ...

for POWER also supported DLPAR, but its dynamic reconfiguration capabilities were limited to CPU capacity and

PCI PCI may refer to: Business and economics * Payment card industry, businesses associated with debit, credit, and other payment cards ** Payment Card Industry Data Security Standard, a set of security requirements for credit card processors * Pro ...

devices, but not memory. In October 2009, seven years after the AIX announcement of DLPAR of memory, CPU and IO slots, Linux finally added the capability to DLPAR memory on POWER systems. The fundamentals of DLPAR are described in the IBM Systems Journal paper titled: "Dynamic reconfiguration: Basic building blocks for autonomic computing on IBM pSeries Servers. Later on, the POWER5 processor added enhanced DLPAR capabilities, including micro-partitioning: up to 10 LPARs can be configured per processor, with a single multiprocessor server supporting a maximum of 254 LPARs (and thus up to 254 independent

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...

instances). There are many interesting applications of DLPAR capabilities. Primarily, it is used to build agile infrastructures, or to automate hardware system resource allocation, planning, and provisioning. This in turn results in increased system utilization. For example, memory, processor or I/O slots can be added, removed or moved to another LPAR, without rebooting the operating system or the application running in an LPAR. IBM DB2 is such application (http://www.ibm.com/developerworks/eserver/articles/db2_dlpar.html), it is aware of the DLPAR events and automatically tunes itself to changing LPAR resources. The

IBM Z IBM Z is a family name used by IBM for all of its z/Architecture mainframe computers. In July 2017, with another generation of products, the official family was changed to IBM Z from IBM z Systems; the IBM Z family now includes the newest mo ...

mainframes and their operating systems, including

Linux on IBM Z Linux on IBM Z or Linux on zSystems is the collective term for the Linux operating system compiled to run on IBM mainframes, especially IBM Z / IBM zSystems and IBM LinuxONE servers. Similar terms which imply the same meaning are ''Linux/390'', ...

, support even more sophisticated forms of dynamic LPARs. Relevant LPAR-related features on those mainframe platforms include

Intelligent Resource Director On IBM mainframes running the z/OS operating system, Intelligent Resource Director (IRD) is software that automates the management of CPU resources and certain I/O resources. IRD is implemented as a collaboration between Workload Manager (WLM) ...

Sysplex In computing, a Parallel Sysplex is a cluster of IBM mainframes acting together as a single system image with z/OS. Used for disaster recovery, Parallel Sysplex combines data sharing and parallel computing to allow a cluster of up to 32 systems ...

Parallel Sysplex In computing, a Parallel Sysplex is a cluster of IBM mainframes acting together as a single system image with z/OS. Used for disaster recovery, Parallel Sysplex combines data sharing and parallel computing to allow a cluster of up to 32 systems ...

, Geographically Dispersed Parallel Sysplex, and HiperSockets. The System z9 supports up to 60 LPARs on a single server, but mainframes also support an additional level of virtualization using

z/VM z/VM is the current version in IBM's VM family of virtual machine operating systems. z/VM was first released in October 2000 and remains in active use and development . It is directly based on technology and concepts dating back to the 1960s, wi ...

with the ability to support thousands of operating system instances on a single server.

See also