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In mainframe computing 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 CPUs, I/O channels and LAN interfaces; when sharing channels, the LPARs can share I/O devices such as direct access storage devices (DASD). PR/SM is integrated with all IBM System z machines. Similar facilities exist on the i and p versions of IBM Power Systems.

IBM introduced PR/SM in 1988 with the IBM 3090 processors.[1]

IBM developed the concept of hypervisors in their CP-40 and CP-67, and in 1972 provided it for the S/370 as Virtual Machine Facility/370.[2] IBM introduced the Start Interpretive Execution (SIE) instruction as part of 370-XA on the 3081, and 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 machines.

External links[edit]

  • "System z PR/SM". Archived from the original on 2019-02-06.


  1. ^ Singh, K., Dymoke-Bradshaw, L., Castiglion, T., Hanninen, P., Junior, V. R., & Kappeler, P. (2010). Security on the IBM Mainframe. IBM Redbooks.
  2. ^ 1990, 2002, Copyright IBM Corp. (2002-04-12). z/VM built on IBM Virtualization Technology General Information Version 4 Release 3.0 (PDF). GC24-5991-04.