System components

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Several system components must work together to implement and support the LPAR environment.

The relationship between processors, firmware, and operating system requires that specific functions need to be supported by each of these components. Therefore, an LPAR implementation is not based solely on software, hardware, or firmware, but on the relationship between the three components. The POWER4 microprocessor supports an enhanced form of system call, known as Hypervisor mode, that allows a privileged program access to certain hardware facilities. The support also includes protection for those facilities in the processor. This mode allows the processor to access information about systems located outside the boundaries of the partition where the processor is located. The Hypervisor does use a small percentage of the system CPU and memory resources, so comparing a workload running with the Hypervisor to one running without the Hypervisor will typically show some minor impacts.

A POWER4-based system can be booted in a variety of partition configurations, including the following:

  • Dedicated hardware system with no LPAR support running so the Hypervisor is not running. This is called a Full System Partition.
  • Partitions running on the system with the Hypervisor running.