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A partition must have an installation method, such as NIM, and a means of running
diagnostics, such as network diagnostics.
Processor
Each LPAR requires at least one physical processor if virtualization is not used. Based on
this, the maximum number of dynamic LPARs per OpenPower 710 server is two without
virtualization. With the use of the IBM Advanced POWER Virtualization, the number of
partitions per processor is 10.
Memory
In a partitioned environment, some of the physical memory areas are reserved by several
system functions to enable partitioning in the partitioning-capable OpenPower server. You can
assign unused physical memory to a partition. You do not have to specify the precise address
of the assigned physical memory in the partition profile, because the system selects the
resources automatically.
The Hypervisor requires memory to support the logical partitions on the server. The amount
of memory required by the Hypervisor varies according to several factors. Factors influencing
the Hypervisor memory requirements include the following:
Number of logical partitions
Partition environments of the logical partitions
Number of physical and virtual I/O devices used by the logical partitions
Maximum memory values given to the logical partitions
Generally, you can estimate the amount of memory required by server firmware to be
approximately 8 percent of the system installed memory. The actual amount required will
generally be less than 8 percent. However, there are some server models that require an
absolute minimum amount of memory for server firmware, regardless of the previously
mentioned considerations.
The minimum amount of physical memory for each partition is 128 MB, but in most cases the
actual requirements and recommendations are between 256 MB and 512 MB for Red Hat and
Novell SUSE. After that, you can assign further physical memory to partitions in increments of
16 MB. This is supported for partitions running Red Hat Enterprise Linux AS 3 (no dynamic
LPAR), Red Hat Enterprise Linux AS 4, and SUSE LINUX Enterprise Server 9. There are
implications on how big a partition can grow based on the amount of memory allocated
initially. For partitions that are initially sized less than 256 MB, the maximum size is 16 times
the initial size. For partitions initially sized 256 MB or larger, the maximum size is 64 times the
initial size.
Note: For a more detailed impression of the amount of memory required by the server
firmware, use the LPAR Validation Tool (LVT). Please refer to "LPAR validation tool" on
page 34.
I/O
The I/O devices are assigned on a slot level to the LPARs, meaning an adapter (either
physical or virtual) installed in a specific slot can only be assigned to one LPAR.
If an adapter has multiple devices, such as the 4-port Ethernet adapter or the Dual Ultra3
SCSI adapter, all devices are automatically assigned to one LPAR and cannot be shared.
Devices connected to an internal controller must be treated as a group. A group can only be
assigned together to one LPAR and cannot be shared.
Chapter 2. Architecture and technical overview
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