Introduction to the HP Virtual Server Environment

Virtual Partitions
Virtual Partitions allow multiple instances of HP-UX to run on a single system or nPartition. This
capability provides finer granularity than nPartitions through the dynamic reallocation of CPUs and
memory between Virtual Partitions. Virtual Partitions are implemented by assigning dedicated
hardware components such as CPU, memory, and I/O to each partition.
Figure 3 illustrates how Virtual Partitions work. Rather than boot HP-UX directly off the hardware, the
vPar Monitor is booted. The vPar Monitor is configured so that it can identify all the partitions as well
as the physical components that belong to each partition. The vPar Monitor loads each Virtual
Partition, which then boots its OS. When the OS queries the kernel to determine what hardware
components are available, the kernel responds with only the subset of the resources that are allocated
to that partition. An advantage to this model is that the Virtual Partition is able to communicate
directly with the hardware resources, resulting in a very low overhead.
Virtual Partitions can adjust the amount of CPUs and memory allocated to each partition while they
are running. This allows CPUs and memory to be moved between Virtual Partitions by deallocating
them from one Virtual Partition and subsequently allocating those same CPUs to another one.
Figure 3. HP-UX Virtual Partitions
HP-UX
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