IBM X3950 X5 Problem Determination And Service Manual page 28

2. Memory Mirroring (CPU and MAX5 mirroring is conditionally supported as
3. DIMM Sparing
4. DDDC Sparing
5. RBS (Redundant Bit Steering) Sparing
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IBM System x3850 X5 and x3950 X5 Types 7145, 7146, 7143, and 7191: Problem Determination and Service Guide
described below.)
a. CPU "Instrasocket" mirroring is supported: the memory controlled by one
CPU memory controller is mirrored to the memory controlled by the second
memory controller of the same CPU.
b. Each of the two mirrored memory cards must have same total memory size
(DIMM population may or may not be the same).
c. Partial mirroring is permitted, when only some CPU's Mirroring
Configuration conditions have been met.
d. MAX5 Mirroring is supported as follows: Port 0 mirrors Port 1 and Port 2
mirrors Port 3, if and only if they have matching DIMM population.
e. CPU and MAX5 Mirroring is enabled by a single setting in UEFI Setup.
f. When CPU mirroring is enabled, UEFI disables CPU Hemisphere mode if it
was previously enabled.
g. MAX5 Mirroring and Hemisphere modes are independent features and both
can be enabled for MAX5.
h. Mirroring is not supported in 2-node with QPI scaling because CPU
Hemisphere mode is required.
i. Although Intel CPUs can support Inter-socket Mirroring in Hemisphere
Mode, IBM eX5 only supports IntraSocket Mirroring.
a. 2 unused DIMMs are spared per memory card.
b. The spare DIMMs must have the same rank and capacity as the largest
DIMMs being spared.
c. The size of the two unused DIMMs for sparing is subtracted from the
usable capacity that is presented to the OS.
d. DIMM sparing is applied on all memory cards in the system.
e. DIMM sparing is only supported on memory controlled by CPUs, i.e. not
available for memory in MAX5.
f. Enabled via "Memory Sparing" setting in UEFI Setup.
g. DIMM sparing disables Hemisphere mode, not a hardware requirement.
h. DIMM sparing is unsupported in 2-node QPI Scaled configuration because
8-socket "glueless" (non-EXA) configurations require Hemisphere mode.
i. Intel CPUs support Rank or DIMM sparing, but IBM eX5 UEFI only
supports DIMM sparing.
a. Intel Double Device Data Correction
b. Similar to RBS, except spare x4 DRAM is designated within each DIMM
pair.
c. Requires Westmere-EX CPUs and x4 DIMMs. x8 DIMM technology is not
supported.
d. Automatically enabled if above requirements are met.
e. Not affected by the "Memory Sparing" setting in UEFI Setup.
f. Runs with Hemisphere Mode enabled.
g. Doesn't lose any memory capacity to provide spare.
a. One x4 DRAM spare maintained in each DIMM pair.
b. Requires x4 DIMMs in MAX5. x8 DIMM technology is not supported.