IBM X3950 X5 Problem Determination And Service Manual page 203

v Double-device data correction support is only available when 16 GB x4 DRAM
technology DIMMs are installed in the memory expansion module and the
memory expansion module is connected to a host server.
v The memory expansion module supports memory sparing through the host
server. Memory sparing reserves memory capacity for failover in the event of a
DIMM failure, and the reserved capacity is subtracted from the total available
memory. When the memory sparing threshold of correctable errors is reached,
the contents of the failing DIMM are copied to the spare memory, and the failing
DIMM or rank is disabled. To enable memory sparing through the Setup utility,
select System Settings > Memory.
v When you populate DIMMs in the memory expansion module, populate the
larger capacity DIMMs first, then the smaller capacity DIMMs. See "Replacing a
memory expansion module DIMM" on page 186 for non-mirroring mode DIMM
population sequence and "Removing a memory expansion module DIMM" on
page 185 for memory-mirroring mode DIMM population sequence.
v The memory expansion module provides eight memory ports (memory
channels), and each memory port supports up to four DIMMs. Do not mix
DIMMs with x4 technology (DIMMs with DRAMs that are organized with 4
data lanes) and x8 technology (DIMMs with DRAMs that are organized with 8
data lanes) in the same memory port. The following table shows the DIMM
connectors on the eight memory ports.
Table 21. DIMM connectors on each memory port
Memory ports
1
2
3
4
5
6
7
8
Note: 2 GB, 4 GB, and 8 GB DIMMs are x4 technology DIMMs. 16 GB and 32 GB DIMMs
are x8 technology DIMMs.
v Do not mix DIMMs with 1 Gb (gigabit) DRAM technology, 2 Gb DRAM
technology, or other gigabit DRAM technologies in banks of eight DIMMs on
memory ports that are on the same memory controller. This is not supported in
the memory expansion module. The following table lists the DIMM connectors
for each bank of eight DIMMs that are on the memory ports within the same
memory controller.
Table 22. DIMM connectors on memory ports with the same memory controller
Bank of DIMMs
1st bank of DIMMs
2nd bank of DIMMs
3rd bank of DIMMs
4th bank of DIMMs
v DIMMs must be installed in pairs for non-mirroring mode and in sets of four for
memory-mirroring.
DIMM connectors
1, 2, 7, and 8
3, 4, 5, and 6
9, 10, 15, and 16
11, 12, 13, and 14
17, 18, 23, and 24
19, 20, 21, and 22
25, 26, 31, and 32
27, 28, 29, and 30
DIMM connectors
1, 2, 3, 4, 5, 6, 7, and 8
9, 10, 11, 12, 13, 14, 15, and 16
17, 18, 19, 20, 21, 22, 23, and 24
25, 26, 27, 28, 29, 30, 31, and 32
Chapter 5. Removing and replacing components
187