4405ch03 Virtualization.fm
Draft Document for Review September 2, 2008 5:05 pm
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IBM Power 570 Technical Overview and Introduction
adapter and a set of Hypervisor calls to operate on them. Virtual TTY does not require the
purchase of any additional features or software such as the PowerVM Edition features.
Depending on the system configuration, the operating system console can be provided by the
Hardware Management Console virtual TTY, IVM virtual TTY, or from a terminal emulator that
is connected to a system port.
3.2 Logical partitioning
Logical partitions (LPARs) and virtualization increase utilization of system resources and add
a new level of configuration possibilities. This section provides details and configuration
specifications about this topic.
3.2.1 Dynamic logical partitioning
Logical partitioning (LPAR) was introduced with the POWER4™ processor-based product line
and the AIX 5L Version 5.1 operating system. This technology offered the capability to divide
a pSeries system into separate logical systems, allowing each LPAR to run an operating
environment on dedicated attached devices, such as processors, memory, and I/O
components.
Later, dynamic logical partitioning increased the flexibility, allowing selected system
resources, such as processors, memory, and I/O components, to be added and deleted from
logical partitions while they are executing. AIX 5L Version 5.2, with all the necessary
enhancements to enable dynamic LPAR, was introduced in 2002. The ability to reconfigure
dynamic LPARs encourages system administrators to dynamically redefine all available
system resources to reach the optimum capacity for each defined dynamic LPAR.
3.2.2 Micro-Partitioning
Micro-Partitioning technology allows you to allocate fractions of processors to a logical
partition. This technology was introduced with POWER5 processor-based systems. A logical
partition using fractions of processors is also known as a Shared Processor Partition or
Micro-Partition. Micro-Partitions run over a set of processors called Shared Processor Pool.
And virtual processors are used to let the operating system manage the fractions of
processing power assigned to the logical partition. From an operating system perspective, a
virtual processor cannot be distinguished from a physical processor, unless the operating
system has been enhanced to be made aware of the difference. Physical processors are
abstracted into virtual processors that are available to partitions. The meaning of the term
physical
processor
in this section is a
processor core
. For example, in a 2-core server there
are two physical processors.
When defining a shared processor partition, several options have to be defined:
The minimum, desired, and maximum processing units. Processing units are defined as
processing power, or the fraction of time the partition is dispatched on physical
processors. Processing units define the capacity entitlement of the partition.
The shared processor pool. Pick one from the list with the names of each configured
shared processor pool. This list also displays the pool ID of each configured shared
processor pool in parentheses. If the name of the desired shared processor pool is not
available here, you must first configure the desired shared processor pool using the
Shared Processor Pool Management window. Shared processor partitions use the default
shared processor pool called DefaultPool by default.
