NEC Express5800 User Manual page 431

NOTE:
capacities less than the actual physical capacities. (The recognized
capacities vary depending on the number of DIMMs and the physical
capacity per DIMM.)
The online spare memory feature can be used under the following conditions:
DIMMs installed in a specific spare set should have the same capacity.

Run SETUP (see Chapter 4), change parameters appropriately in the [Sparing] menu

selected as shown below, save the settings and exit from SETUP.
[Advanced] → [Memory Configuration] submenu → [Memory RAS Mode] → [Sparing]
Run SETUP again, and make sure that the status of additionally installed DIMM is shown

as [Sparing].
Install memory devices in the following order:

2-CPU 1-CPU
configuration configuration
1 1
3 2
1 1
3 2
1 1
3 2
The following sparing can be neither configured nor set.
The DIMMs of different capacities are installed.

The operating system recognizes the DIMMs as those with
REAR
Upgrading Your Server 9-93
Mother board
2-CPU
configuration
4
2
4
2
4
2
FRONT