Memory Sparing - NEC Express5800/R120b-1 User Manual

9-38 Upgrading Your Server

Memory sparing

Memory sparing is a feature whereby channel 2 of the memory controller in each CPU is designated
as a "spare" channel and the DIMMs (memories) that use that channel are put on standby so that
operations can be automatically switched to a standby DIMM if a correctable error occurs in one of
the DIMMs operating under the control of the memory controller, allowing processing to continue
unimpeded.
IMPORTANT:
The memory sparing feature is not supported by the N8100-1654F/1660F.
Additional memory sticks (N8102-371/372/373/374/375) are required to use the
memory sparing feature.
The capacity of the additional memory sticks must match the capacity of the other
memory sticks used in the server.
Example: Memory sparing in a 2-CPU configuration
Spare set #3
Spare set #1
Spare set #4
Spare set #2
CPU1
Memory controller
CH0
CPU1-DIMM 4 CPU1-DIMM 5
CPU1-DIMM 1 CPU1-DIMM 2
Operating
CPU2
Memory controller
CH0
CPU2-DIMM 4 CPU2-DIMM 5
CPU2-DIMM 1 CPU2-DIMM 2
Operating
CH1
CH2
CPU1-DIMM 6
CPU1-DIMM 3
Waiting
(spare)
CH1
CH2
CPU2-DIMM 6
CPU2-DIMM 3
Waiting
(spare)