Lenovo ThinkServer TD340 User Manual And Hardware Maintenance Manual page 109

Memory module installation order in sparing mode
This section explains the memory module installation order in sparing mode. The sparing mode provides
memory redundancy. In this mode, the RAS features are available. For more information about the RAS
features, refer to the related section in "Features" on page 7.
Note: It is recommended that all memory modules to be installed must be the same type (LV RDIMM,
RDIMM, or UDIMM) with the same capacity, frequency, voltage, and number of ranks.
Your server supports rank sparing mode. In rank sparing mode, one rank of a memory module works as the
spare rank for the other ranks on the same channel. The spare rank is not available as system memory. To
enable rank sparing mode, ensure that:
• At least three ranks are available in one channel.
• The capacity of the spare rank must be the same with or larger than the capacity of other ranks within
the same channel.
The following table explains the memory module installation order for servers that have only one
microprocessor (CPU1) installed.
Table 11. Memory module installation order in sparing mode for servers with one microprocessor
CPU1 DIMM
DIMM installation order
The following table explains the memory module installation order for servers that have two microprocessors
(CPU1 and CPU2) installed.
Table 12. Memory module installation order in sparing mode for servers with two microprocessors
DIMM installation order
Memory module installation order in lockstep mode
This section explains the memory module installation order in lockstep mode. In this mode, the RAS features
are available. For more information about the RAS features, refer to the related section in "Features" on
page 7.
Notes:
• In this mode, slots A1 and A2 cannot be populated.
• In this mode, slots B1 and B2 must be populated identically as slots C1 and C2.
• All memory modules to be installed on a server must be the same type (LV RDIMM, RDIMM, or UDIMM)
with the same capacity, frequency, voltage, and number of ranks.
The following table explains the memory module installation order for servers that have only one
microprocessor (CPU1) installed.
Table 13. Memory module installation order in lockstep mode for servers with one microprocessor
CPU1 DIMM
DIMM installation order
A1 A2
1 2
CPU1 DIMM
A1 A2 B1 B2
1 2 5 6
A1 A2
B1 B2
3 4
C1 C2 D1 D2
9 10 3 4
B1 B2
1 3
.
Chapter 6 Installing, removing, or replacing hardware
C1 C2
5 6
CPU2 DIMM
E1 E2 F1 F2
7 8 11 12
C1 C2
2 4
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