NEC Express5800/R120b-1 User Manual page 391

The memory mirroring feature can be used under the following conditions:
Install memory devices on two memory sockets configuring a mirror set.
All the installed memory devices should have the same capacity.
Run SETUP (described on page 4-2), change parameters appropriately in the [Mirror]
menu selected as shown below, save the settings and exit from SETUP.
[Advanced] → [Memory Configuration] → [Memory RAS Mode] → [Mirror]
After SETUP finishes, rerun SETUP and make sure that the installed DIMM status is
[Mirror].
Install memory devices in the following order.
1-CPU 2-CPU
configuration configuration
2
4
2
4
2
3
1
1
2
3
1
1
The following mirroring cannot be configured:
Memory mirroring within a specific memory channel
Notes on configuring memory mirroring
In memory mirroring configuration, [Memory RAS Mode] menu is changed from "Mirror" to
"Independent" in the following cases:
When you additionally install DIMMs that unable to configure memory mirroring
When you remove DIMMs that takes down the memory mirroring
FRONT
CPU2-DIMM 3
CPU2-DIMM 6
CPU2-DIMM 2
CPU2-DIMM 5
CPU2-DIMM 1
CPU2-DIMM 4
CPU2
CPU1
CPU1-DIMM 4
CPU1-DIMM 1
CPU1-DIMM 5
CPU1-DIMM 2
CPU1-DIMM 6
CPU1-DIMM 3
Upgrading Your Server 9-35
Mother board
REAR