Configuration Rules 2-9
When you are defining two partitions, you may have from two to five memory
modules, depending on the number of CPU and I/O modules in the system.
Memory is always allocated on module boundaries. Set the interleave
environment variable to none, as noted in Chapter 4.
The console firmware allocates the largest sized module to partition 0, and the
smallest module to partition 1. It then attempts to distribute the remaining
modules such that as equal an amount is given to both partitions as is possible.
Figure 2–4 shows some examples. Item A declares that when there are an even
number of modules of equal size, the memory is divided equally. Item B
illustrates an odd number of modules of equal size. Here, the distribution is as
equal as possible, with the largest amount of memory going to partition 0, and
the next-largest, to partition 1.
Item C shows some examples of a series of modules of varying size. In general,
the largest memory module is allocated to partition 0, and the smallest, to
partition 1. The remaining modules are divided so as to make the allocation for
the two partitions as equal as possible. When a situation arises to make both
partitions unequal with the same ratio, the firmware makes partition 0 the
largest partition (case 3, below).
1.
Here, the 4 G-byte memory is allocated to partition 0, and the 1 G-byte
memory is allocated to partition 1. There are two remaining 2-Gbyte
modules, and they are distributed so as to make the partitions as equal as
possible, giving both 2-Gbyte modules to partition 1, creating partition 0
with 4 Gbytes and partition 1 with 5 Gbytes.
2.
Here, a 2 G-byte memory is allocated to partition 0, and the 1-Gbyte
memory is allocated to partition 1. The remaining 2-Gbyte memory is given
to partition 1, since a 3 G-byte/2-Gbyte allocation is more equal than
allocating 4 Gbyte to partition 0 and 1 Gbyte to partition 1.
3.
Here, a 2 G-byte memory is allocated to partition 0, and a 1-Gbyte memory
is allocated to partition 1. Either way the remaining 2 Gbyte memories are
allocated (both to partition 1, or 1 to partition 0 and 1 to partition 1), the
memory allocation will be 3-Gbyte/2-Gbyte, so the default is to make
partition 0 the largest partition.
