IBM eserver p Series Service Manual page 45

Available System Memory
18 GB to 32 GB
34 GB to 48 GB
50 GB to 64 GB
Before calculating the memory that is available for partitions, the appropriate memory overhead must be
subtracted from the system memory.
Memory Placement Considerations for LPAR Environment
If the system is running AIX 5.1 in LPAR mode and partitions with more than 16 GB of memory are
desired, special consideration must be given to DIMM placement.
Allocating a partition with more than 16 GB of memory requires the following:
v The system must have more than 33 GB of memory to run one AIX 5.1 partition with 16 GB or more of
memory allocated to it, and the first processor card must have a minimum of 16 GB of memory.
v The system must have more than 49 GB of memory to run two AIX 5.1 partitions with 16 GB or more
assigned to them, and the first and second processor card must each have a minimum of 16 GB of
memory.
Note: Memory configurations of new systems have balanced memory across all processors for optimum
performance. Memory quads may have to be reconfigured to allow AIX 5.1 partitions to function
with more than 16 GB of memory allocated to them.
If the system is running AIX 5.2 or Linux, selecting Small Real Mode when setting the memory profile in a
partition allows a partition with more than 16 GB of memory to be created regardless of the memory
configuration.
The following table details the number of logical partitions that can be created based on the amount of
memory installed in the system, the amount of memory allocated to the partitions, the version of the
operating system, and the version of the system firmware.
Approximate
Memory Overhead
Required by
Total Memory Firmware
4 GB .75 to 1 GB
8 GB .75 to 1 GB
16 GB .75 to 1 GB
24 GB 1 to 1.25 GB
32 GB 1 to 1.25 GB
48 GB 1.25 to 1.75 GB
64 GB 1.5 to 2 GB
Notes:
1. All partition maximum numbers are subject to availability of sufficient processor, memory, and I/O
resources to support that number of partitions. For example, a system with eight processors can
support a maximum of eight partitions.
Firmware Overhead usage
1 to 1.25 GB
1.25 to 1.75 GB
1.5 to 2 GB
Maximum Number of
Partitions:
AIX 5.1
Approximate Partitions ≤ 16GB and
Usable Partition Partitions > 16GB
Memory (see Notes 1 and 2)
3 to 3.25 GB 8 and 0
7 to 7.25 GB 8 and 0
15 to 15.25 GB 8 and 0
22.75 to 23 GB 8 and 0
30.75 to 31 GB 8 and 0
46.25 to 46.75 GB 8 and 1
62 to 62.5 GB 8 and 2
Maximum Number of
Partitions:
AIX 5.2 (or later) or
Linux
All partition sizes (see
Notes 1, 3, and 4)
8
8
8
8
8
8
8
Chapter 1. Reference Information
25