v The server supports non-mirroring mode, memory mirroring mode, and memory
sparing mode. For more information and the DIMM population for
non-mirroring mode, see “Non-mirroring (independent mode).” For more
information and the DIMM population sequence for memory mirroring, see
“Memory mirroring.” For more information and the DIMM population sequence
for memory sparing, see “Memory sparing” on page 48.
Non-mirroring (independent mode)
Use this information for DIMM population of the server for non-mirroring
(independent mode).
When you use non-mirroring mode, follow the DIMM population sequence as
indicated in the following table..
Note: When you install an optional microprocessor and memory expansion tray in
the server, microprocessors 3 and 4 must be installed as a pair. The server does not
support a configuration of three microprocessors.
Table 9. DIMM population sequence for non-mirroring mode (independent mode)
Number of
installed
microprocessors
DIMM connector population sequence on
the system board
DIMM connector population sequence on
the microprocessor and memory expansion
tray
1 1, 12, 4, 9, 2, 11, 5, 8, 3, 10, 6, 7
2 1, 13, 12, 24, 4, 16, 9, 21, 2, 14, 11, 23, 5, 17, 8,
20, 3, 15, 10, 22, 6, 18, 7, 19
4 1, 13, 12, 24, 4, 16, 9, 21, 2, 14, 11, 23, 5, 17, 8,
20, 3, 15, 10, 22, 6, 18, 7, 19
25, 37, 36, 48, 28, 40, 33, 45, 26, 38, 35, 47, 29,
41, 32, 44, 27, 39, 34, 46, 30, 42, 31, 43
Memory mirroring
Use this information for DIMM population of the server for memory mirroring.
Memory-mirroring replicates and stores data on DIMMs across two or four
channels simultaneously. If a failure occurs, the memory controller switches from
the DIMMs on the primary channel to the DIMMs on the backup channel. To
enable memory mirroring through the Setup utility, select System Settings →
Memory → Memory Mode. For more information, see “Using the Setup utility” on
page 142.
When you use memory mirroring mode, consider the following information:
v The server supports single-socket memory mirroring. Memory channel 0 mirrors
channel 1, and memory channel 2 mirrors channel 3. This mirroring provides
redundancy in memory but reduces the total memory capacity in half.
v DIMMs must be installed in pairs for each microprocessor when using the
memory mirroring feature.
v The DIMM population must be identical for memory channel 0 and memory
channel 1, and identical for memory channel 2 and memory channel 3.
v Memory mirroring reduces the maximum available memory by half of the
installed memory. For example, if the server has 64 GB of installed memory, only
32 GB of addressable memory is available when memory mirroring is enabled.
v The following table lists the DIMM installation sequence for memory-mirroring
mode.
46 System x3750 M4 Types 8722 and 8733: Installation and Service Guide
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