IBM 71413SU - System x3950 M2 Reference page 28

Note: As previously mentioned, hot-add and hot-swap are mutually exclusive. You can
only enable
The requirements are as follows:
Operating system support: Adding usable system memory to a running operating system
requires operating system support. This is done with an ACPI sequence. Currently, the
only operating system that has this capability and is supported on the x3850 M2 and
x3950 M2 is Windows Server 2003, Enterprise Edition or Datacenter Edition.
Memory hot-add must be specifically enabled in the BIOS setup. When this is done, the
system allocates blank windows of memory space for future memory additions. By
enabling hot-add, memory mirroring will automatically be disabled.
Memory cards 2 and 4 must not be installed yet because these are the
be hot-added.
If only one memory card, memory card 1, is installed prior to the hot-add operation, then
only
If two memory cards are installed in slots 1 and 3, then two additional memory cards can
be added in slots 2 and 4.
The DIMMs must be add in matched pairs, that is, two at a time, and they must also match
the equivalent pair of DIMMs on the matching memory card on the other power bus.
A minimum of 4 GB of memory must be installed in the server for hot-add memory to be
available. Additionally, for 32-bit operating systems, the Physical Address Extension
(PAE) mode has to be enabled to take advantage of the additional memory.
For information about how to perform a hot-add operation, and more information about the
restrictions, refer to x3850 M2 and x3950 M2 User's Guide.
Note: Observe the following concepts when hot-adding memory.
If you plan to enable hot-add memory and you have a x3850 M2 and x3950 M2 system
that comes standard with two memory cards, you need to move memory card 2 to slot 3
to be able to hot-add memory cards in slots 2 and 4.
After you have added a memory card with two DIMMs, you cannot add more memory to
that same memory card without powering off the server.
Enabling hot-add reserves a portion of the memory map for the memory that can be
hot-added in the future. If you do not plan to use hot-add, we recommend that you do
not enable this feature in BIOS.
Memory configuration in BIOS
Configure the memory subsystem in the server's BIOS Setup menu by clicking Advanced
Settings -> Memory Settings -> Memory Array Setting. The choices are listed in Table 11.
Table 11 Memory configuration modes in BIOS
Mode
HPMA (high performance memory array)
FAMM (full array memory mirroring)
HAM (hot-add memory)
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IBM System x3950 M2 and x3850 M2 Technical Introduction
one
of these features.
one additional memory card may be added in slot 2.
Memory Memory-
ProteXion mirroring
Yes Disabled
Yes Yes
Yes Disabled
only ones that can
Hot-swap Hot-add
memory memory
Disabled Disabled
Yes Disabled
Disabled Yes