IBM BladeCenter PS703 Technical Overview And Introduction

Also see for BladeCenter PS703: Service guide

Contents

100 IBM BladeCenter PS703 and PS704 Technical Overview and IntroductionThe POWER Hypervisor abstracts the physical processors and presents a set of virtualprocessors to the operating system within the micro-partitions on the system. The operatingsystem sees only the virtual processors and dispatches runable tasks to them in the normalcourse of running a workload.From an operating system perspective, a virtual processor cannot be distinguished from aphysical processor unless the operating system has been enhanced to be made aware of thedifference. Physical processors are abstracted into virtual processors that are available topartitions. The meaning of the term physical processor in this section is a processor core.When defining a shared processor partition, several options must be defined: Processing unitsThe minimum, desired, and maximum processing units. Processing units are defined asprocessing power, or the fraction of time that the partition is dispatched on physicalprocessors. Processing units define the capacity entitlement of the partition. Cap or Uncap partitionSelect whether or not the partition can access extra processing power to “fill up” its virtualprocessors beyond its capacity entitlement, selecting either to cap or uncap your partition.If spare processing power is available in the processor pool or other partitions are notusing their entitlement, an uncapped partition can use additional processing units if itsentitlement is not enough to satisfy its application processing demand. WeightThe weight (preference) in the case of an uncapped partition. Virtual processorsThe minimum, desired, and maximum number of virtual processors. A virtual processor isa depiction or a representation of a physical processor that is presented to the operatingsystem running in a micro-partition.The POWER Hypervisor calculates a partition’s processing power based on minimum,desired, and maximum values, processing mode and on other active partitions’ requirements.The actual entitlement is never smaller than the processing units desired value but canexceed that value in the case of an uncapped partition and can be up to the number of virtualprocessors allocated.A partition can be defined with a processor capacity as small as 0.10 processing units. Thisrepresents 0.1 of a physical processor. Each physical processor can be shared by up to 10shared processor partitions and the partition’s entitlement can be incremented fractionally byas little as 0.01 of the processor. The shared processor partitions are dispatched andtime-sliced on the physical processors under control of the POWER Hypervisor. The sharedprocessor partitions are created and managed by the HMC or Integrated VirtualizationManagement.Partitioning maximums on the POWER7-based blades are as follows: The PS703 can have 16 dedicated partitions or up to 160 micro-partitions The PS704 can have 32 dedicated partitions or up to 320 micro-partitionsIt is important to point out that the maximums stated are supported by the hardware, but thepractical limits depend on the application workload demands.The following list details additional information about virtual processors: A virtual processor can be running (dispatched) either on a physical processor or asstandby waiting for a physical processor to became available.