Specifications

5102ch03.fm Draft Document for Review May 12, 2014 12:46 pm
76 IBM Power System S822 Technical Overview and Introduction
3.1 POWER Hypervisor
Combined with features in the POWER8 processors, the IBM POWER Hypervisor delivers
functions that enable other system technologies, including logical partitioning technology,
virtualized processors, IEEE VLAN-compatible virtual switch, virtual SCSI adapters, virtual
Fibre Channel 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 “Processing mode”
on page 88).
򐂰 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 performs a reset or 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 managed console. It requires memory to support the resource
assignment to the logical partitions on the server. The amount of memory that is required by
the POWER Hypervisor firmware varies according to several factors:
򐂰 Number of logical partitions
򐂰 Number of physical and virtual I/O devices used by the logical partitions
򐂰 Maximum memory values specified in the logical partition profiles
The minimum amount of physical memory that is required to create a partition will be the size
of the system’s logical memory block (LMB). The default LMB size varies according to the
amount of memory that is configured in the CEC (Table 3-1).
Table 3-1 Configured CEC memory-to-default logical memory block size
In most cases, however, the actual minimum requirements and recommendations of the
supported operating systems are greater than 256 MB. Physical memory is assigned to
partitions in increments of LMB.
The POWER Hypervisor provides the following types of virtual I/O adapters:
򐂰 Virtual SCSI
򐂰 Virtual Ethernet
򐂰 Virtual Fibre Channel
򐂰 Virtual (TTY) console
Configurable CEC memory Default logical memory block
Up to 32 GB 128 MB
Greater than 32 GB 256 MB