4405ch03 Virtualization.fm Draft Document for Review September 2, 2008 5:05 pm
76 IBM Power 570 Technical Overview and Introduction
3.1 POWER Hypervisor
Combined with features designed into the POWER6 processors, the POWER Hypervisor
delivers functions that enable other system technologies, including logical partitioning
technology, virtualized processors, IEEE VLAN compatible virtual switch, virtual SCSI
adapters, and virtual consoles. The POWER Hypervisor is a basic component of the system’s
firmware and offers the following functions:
Provides an abstraction between the physical hardware resources and the logical
partitions that use them.
Enforces partition integrity by providing a security layer between logical partitions.
Controls the dispatch of virtual processors to physical processors (see 3.2.3, “Processing
mode” on page 79).
Saves and restores all processor state information during a logical processor context
switch.
Controls hardware I/O interrupt management facilities for logical partitions.
Provides virtual LAN channels between logical partitions that help to reduce the need for
physical Ethernet adapters for inter-partition communication.
Monitors the Service Processor and will perform a reset/reload if it detects the loss of the
Service Processor, notifying the operating system if the problem is not corrected.
The POWER Hypervisor is always active, regardless of the system configuration and also
when not connected to the HMC. It requires memory to support the resource assignment to
the logical partitions on the server. The amount of memory required by the POWER
Hypervisor firmware varies according to several factors. Factors influencing the POWER
Hypervisor memory requirements include the following:
Number of logical partitions.
Number of physical and virtual I/O devices used by the logical partitions.
Maximum memory values given to the logical partitions.
The minimum amount of physical memory to create a partition is the size of the system’s
Logical Memory Block (LMB). The default LMB size varies according to the amount of
memory configured in the CEC as shown in Table 3-1.
Table 3-1 Configurable CEC memory-to-default Logical Memory Block size
But in most cases, the actual requirements and recommendations are between 256 MB and
512 MB for AIX, Red Hat, and Novell SUSE Linux. Physical memory is assigned to partitions
in increments of Logical Memory Block (LMB).
The POWER Hypervisor provides the following types of virtual I/O adapters:
Virtual SCSI
Configurable CEC memory Default Logical Memory Block
Less than 4 GB 16 MB
Greater than 4 GB up to 8 GB 32 MB
Greater than 8 GB up to 16 GB 64 MB
Greater than 16 GB up to 32 GB 128 MB
Greater than 32 GB 256 MB
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