User's Guide

Upgrading Your Server 9-35
Using the Memory RAS Features
The server has RAS feature including "Standard memory configuration (x4 SDDC ECC memory)",
a "memory mirroring feature", a "memory sparing feature", and a "LockStep (x8 SDDC ECC
memory) feature". SDDC (Single Device Data Correction) allows automatic correction of memory
error (multi-bit error).
IMPORTANT:
 To use the memory mirroring feature or LockStep (x8 SDDC ECC
memory) feature, an additional memory stick
(N8102-387/388/389/390/391) is required.
 To use x4 SDDC ECC memory feature, an additional memory stick
(N8102-371/372/373/374/375) is required.
The memory area on the motherboard of the server is divided into two memory channels as shown
in the figure below.
Memory controller Memory controller
CPU2-DIMM3
CPU1-DIMM1
CPU1-DIMM4
CPU1-DIMM2
CPU1-DIMM5
CPU1-DIMM3
CPU1-DIMM6
CPU2-DIMM4
CPU2-DIMM1
CPU2-DIMM5
CPU2-DIMM2
CPU2-DIMM6
Memory controller
CH0 CH0 CH1
CH1
CH2 CH2
CPU1
CPU2
Memory controller
The memory mirroring and LockStep features keep memory redundancy between memory channels
by monitoring or altering memory active/inactive status, respectively.