Intel E7-2803 AT80615006438AB User Manual

Product codes
AT80615006438AB
Page of 50
Datasheet Volume 2 of 2
33
Memory Controller (Mbox)
7.5
Partial Memory Mirroring
Partial memory mirroring is a mirror mode of operation with parts of system memory 
operating with redundant memory at slave, leaving the rest of the system memory in 
non-mirror mode. The granularity of the partial memory that gets to operate in mirror 
mode is implementation dependent. On the Intel Xeon Processor E7-8800/4800/2800 
Product Families, the granularity is defined to be at the Home Agent level, meaning 
either all of the memory behind the Home Agent is mirrored or it is not.  
Partial Memory Mirroring provides additional flexibility to the platform to optimize cost/
performance/RAS by providing higher degree of reliability to memory segment that is 
deemed to be containing the most critical content, at lower cost than mirroring the 
entire system memory. 
7.5.1
Usage Model
Memory Mirroring is a RAS feature that enables duplicating memory content at a 
remote DIMM in the partition. This capability enables high data availability from 
memory subsystem, which due to its large cell array, is prone to various error types.  
Partial Memory Mirroring enables you to select the segments of system memory  that 
will be containing the most critical code, that is, Kernel codes, to operate with higher 
degree of reliability than the rest of the data. OEM will need to have control over the OS 
to load the critical code/data into the mirrored memory region. This form of partial 
mirror configuration  is done statically at power up, with no dynamic readjustment to 
the configuration. This usage model is enabled for the Intel Xeon processor 7500 
series-based platform.
'Mirroring within a memory controller is not supported.
7.5.2
Overview
The Intel
®
 Xeon
®
 Processor 7500 Series-based platform enables memory mirroring 
operation by making use of two directly connected socket's  Home Agent/
memory_controller as the master mirror agent, and an identical Home Agent/
memory_controller as slave agent. In partial memory configuration, the platform BIOS/
BMC, will configure only one pair of Home Agents in mirror mode, leaving the rest of 
Home Agents in non-mirror.