Logical partition: Difference between revisions

Revision as of 15:46, 22 September 2019

Revision as of 17:14, 17 February 2020

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==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 FeatureFacility){{clarify|date=April 2016}} 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 |accessdate=2010-01-14 |first=Karan |last=Singh}}</ref>