Lenovo System x3750 M4, Installation And Service Manual

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Table 9. DIMM population sequence for memory mirroring mode (continued)
DIMMs
Number of
microprocessors
DIMM connector
population sequence
on the system board
DIMM connector
population sequence
on the optional
microprocessor and
memory expansion tray
2nd set 4 9, 12, 21, 24 33, 36, 45, 48
3rd set 4 2, 5, 14, 17 26, 29, 38 41
4th set 4 8, 11, 20, 23 32, 35, 44, 47
5th set 4 3, 6, 15, 18 27, 30, 39, 42
6th set 4 7, 10, 19, 22 31, 34, 43, 46
Note: The server does not support a configuration of three microprocessors. The server supports one, two, or
four microprocessors only.
Memory sparing
This section contains information pertaining to the memory-sparing mode of operation.
In the memory-sparing mode, one rank is held in reserve as a spare of the other ranks in the same channel.
The server supports memory sparing. 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. Memory sparing
provides less redundancy than memory mirroring does. If a predetermined 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
→
Memory Mode .
When you use the memory sparing mode, consider the following information:
• When single-rank or dual-rank DIMMs are used, at least three DIMMs must be installed to support
memory sparing.
• Each memory channel supports three DIMMs. The third DIMM in each channel is the sparing DIMM for all
of the DIMMs in the channel.
• When quad-rank DIMMs are used, one of the ranks in the DIMM itself is used for sparing.
• The server does not support the mixing of single and dual-rank registered DIMMs (RDIMM) with quad-rank
load-reduced DIMMs (LR-DIMM).
The following table shows the DIMM population sequence for the memory-sparing mode.
Note: The server does not support a configuration of three microprocessors. The server supports one, two,
or four microprocessors only.
Table 10. DIMM population sequence for memory sparing mode
DIMMs
Number of
microprocessors
DIMM connector
population sequence
on the system board
DIMM connector
population sequence
on the optional
microprocessor and
memory expansion tray
One microprocessor
1st set 1 1, 2, 3
2nd set 1 10, 11, 12
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Lenovo System x3750 M4 Installation and Service Guide