Memory mirroring mode installation order

Memory-mirroring mode provides full memory redundancy while reducing the total system memory capacity in half. Memory channels are grouped in pairs with each channel receiving the same data. If a failure occurs, the memory controller switches from the DIMMs on the primary channel to the DIMMs on the backup channel. The DIMM installation order for memory mirroring varies based on the number of processors and DIMMs installed in the server.

Memory mirroring guidelines:

Memory mirroring reduces the maximum available memory by half of the installed memory. For example, if the server has 64 GB of installed memory, only 32 GB of addressable memory is available when memory mirroring is enabled.
Each DIMM must be identical in size and architecture.
DIMMs on each memory channel must be of equal density.
If two memory channels have DIMMs, mirroring occurs across two DIMMs (channels 0/1 will both contain the primary/secondary memory caches).
If three memory channels have DIMMs, mirroring occurs across all three DIMMs (channels 0/1, channels 1/2, and channels 2/0 will all contain primary/secondary memory caches).
Partial Memory Mirroring is a sub-function of memory mirroring. It requires following the memory installation order of memory mirroring mode.
Before installing 24Gbit (96 GB) memory module to the system, make sure to update the UEFI firmware to the latest version first, then remove all existing 16Gbit (16 GB, 32 GB, 64 GB, 128 GB, 256 GB) memory modules.

Table 1. Memory mirroring mode
Total DIMMs	Processor 0/1/4/5
Total DIMMs	D1	D2	C1	C2	B1	B2	A1	A2	E2	E1	F2	F1	G2	G1	H2	H1
64 DIMMs	D1		C1		B1		A1			E1		F1		G1		H1
128 DIMMs	D1	D2	C1	C2	B1	B2	A1	A2	E2	E1	F2	F1	G2	G1	H2	H1
Total DIMMs	Processor 2/3/6/7
Total DIMMs	M1	M2	L1	L2	K1	K2	J1	J2	N2	N1	P2	P1	R2	R1	T2	T1
64 DIMMs	M1		L1		K1		J1			N1		P1		R1		T1
128 DIMMs	M1	M2	L1	L2	K1	K2	J1	J2	N2	N1	P2	P1	R2	R1	T2	T1

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