PR/SM
Processor Resource/Systems Manager: the mainframe firmware that creates LPARs and shares the processors between them.
Also written PRSM, Processor Resource/Systems Manager, LPAR weight, LPAR hypervisor, capping
PR/SM, Processor Resource/Systems Manager, is built into the mainframe's firmware. It is the layer that makes LPARs possible: it divides the machine's processors, memory and I/O between the LPARs and keeps them separate.
Processors can be given to an LPAR in two ways. Dedicated processors belong to one LPAR only. Shared processors are shared between several LPARs, and PR/SM decides from moment to moment which LPAR uses them. Each LPAR has a weight that sets its fair share when processors are busy. An LPAR with weight 600 gets about twice as much as one with weight 300 when both want more than is available.
LPARs can also be capped, so they never use more than a set amount even when processors are free. Capping is used to control software costs, since many products are priced on processor use.
PR/SM and WLM work at different levels. PR/SM shares the machine between LPARs. WLM, inside each z/OS system, shares that system's part between its work. When a system is short of processor time, the cause may be at either level.
Where can I learn this hands-on?
Right here, at ZedBank. You take a junior job at a simulated bank and learn each part of the work by doing it, with Zed beside you. There's nothing to install.
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- LPARA logical partition: one physical mainframe carved into several independent virtual machines, each running its own operating system.
- IBM ZIBM's current family of mainframe hardware, and the brand name you will see on most modern mainframe job adverts.
- HMCThe Hardware Management Console: the workstation used to control the mainframe hardware, its LPARs and IPLs.
- WLMWorkload Manager: the part of z/OS that decides which work gets the processor, memory and disk access first, based on goals the site sets.
- MIPSMillions of instructions per second: the common, rough way of describing how much processing capacity a mainframe has.
- Specialty engineA mainframe processor set aside for one kind of work, such as Linux or certain z/OS workloads, and usually priced lower than a general processor.