Memory Sparing - NEC Express5800/R120b-2 User Manual

9-40 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
N8100-1644F/1650F.
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
NOTE:
system is less than the DIMMs' physical capacity. The capacity
recognized by the operating system depends on the number of memory
sticks inserted and the capacity of each stick.
CH0
CPU1-DIMM 4
Spare set #3
CPU1-DIMM 1
Spare set #1
CH0
Spare set #4
CPU2-DIMM 4
Spare set #2
CPU2-DIMM 1
The capacity of the DIMMs recognized by the operating
CPU1
Memory controller
CH1
CPU1-DIMM 5 CPU1-DIMM 6
CPU1-DIMM 2 CPU1-DIMM 3
Operating
On standby (spare)
CPU2
Memory controller
CH1
CPU2-DIMM 5 CPU2-DIMM 6
CPU2-DIMM 2 CPU2-DIMM 3
Operating On standby (spare)
CH2
CH2