User Guide

With memory sparing enabled, the system memory available to the operating system is reduced by one rank per
channel. For example, in a dual-processor configuration with sixteen 4 GB dual-rank DIMMs, the available system
memory is: 3/4 (ranks/channel) × 16 (DIMMs) × 4 GB = 48 GB, and not 16 (DIMMs) × 4 GB = 64 GB.
NOTE
: Memory sparing does not offer protection against a multi-bit uncorrectable error.
NOTE
: Both Advanced ECC/Lockstep and Optimizer modes support Memory Sparing.
Memory Mirroring
Memory Mirroring offers the strongest DIMM reliability mode compared to all other modes, providing improved
uncorrectable multi-bit failure protection. In a mirrored configuration, the total available system memory is one half of
the total installed physical memory. Half of the installed memory is used to mirror the active DIMMs. In the event of an
uncorrectable error, the system will switch over to the mirrored copy. This ensures SDDC and multi-bit protection.
Memory installation guidelines:
• Memory modules must be identical in size, speed, and technology.
• DIMMs installed in memory sockets with white release levers must be identical and similar rule applies for sockets
with black and green release tabs. This ensures that identical DIMMs are installed in matched pairs - for example,
A1 with A2, A3 with A4, A5 with A6, and so on.
Sample memory configurations
The following tables show sample memory configurations for one and two processor configurations that follow the
appropriate memory guidelines stated in this section.
NOTE
: 16 GB quad-rank RDIMMs are not supported.
NOTE
: 1R, 2R and 4R in the following tables indicate single-, dual-, and quad-rank DIMMs respectively.
Table 1. Memory configurations—single processor
System Capacity
(in GB)
DIMM Size (in
GB)
Number of
DIMMs
DIMM Rank, Organization,
and Frequency
DIMM Slot Population
2 2 1
1R, x8, 1333 MT/s,
1R, x8, 1600 MT/s
A1
4 2 2
1R, x8, 1333 MT/s,
1R, x8, 1600 MT/s
A1, A3
8 2 4
1R, x8, 1333 MT/s,
1R, x8, 1600 MT/s
A1, A2, A3, A4
12 2 6
1R, x8, 1333 MT/s,
1R, x8, 1600 MT/s
A1, A2, A3, A4, A5, A6
16 2 8
1R, x8, 1333 MT/s A1, A2, A3, A4, A5, A6, A7, A8
4 4
2R, x8, 1333 MT/s,
2R, x8, 1600 MT/s
A1, A2, A3, A4
24 2 12
1R, x8, 1333 MT/s A1, A2, A3, A4, A5, A6, A7, A8, A9, A10,
A11, A12
4 6
2R, x8, 1333 MT/s,
2R, x8, 1600 MT/s
A1, A2, A3, A4, A5, A6
48 4 12
2R, x8, 1333 MT/s A1, A2, A3, A4, A5, A6, A7, A8, A9, A10,
A11, A12
44