IBM 71413SU Technical Reference - Page 28

Note: As previously mentioned, hot-add and hot-swap are mutually exclusive. You can only enable one of these features. 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 only ones that can be hot-added. If only one memory card, memory card 1, is installed prior to the hot-add operation, then only one additional memory card may be added in slot 2. 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 Memory ProteXion HPMA (high performance memory array) Yes FAMM (full array memory mirroring) Yes HAM (hot-add memory) Yes Memorymirroring Disabled Yes Disabled Hot-swap memory Disabled Yes Disabled Hot-add memory Disabled Disabled Yes 28 IBM System x3950 M2 and x3850 M2 Technical Introduction