Dell PowerEdge FC830 Owner's Manual page 61

In this mode, one rank per channel is reserved as a spare. If persistent correctable errors are detected on a rank, the data from
this rank is copied to the spare rank, and the failed rank is disabled.
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 single-rank memory modules, the available system memory is: 3/4
(ranks/channel) × 16 (memory modules) × 4 GB = 48 GB, and not 16 (memory modules) × 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.
Related references
System Setup on page 19
Memory mirroring
Memory mirroring offers the strongest memory module 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 memory modules. In the event of an
uncorrectable error, the system switches over to the mirrored copy. This ensures SDDC and multi-bit protection.
The installation guidelines for memory modules are as follows:
● Memory modules must be identical in size, speed, and technology.
● Memory modules installed in memory module sockets with white release levers must be identical and the same rule applies
for sockets with black and green release tabs. This ensures that identical memory modules are installed in matched pairs—
for example, A1 with A2, A3 with A4, A5 with A6, and so on.
Table 22. Processor configuration
Processor Configuration
Single CPU Memory population order
Sample memory configurations
The following tables show sample memory configurations that follow the appropriate memory guidelines stated in this section.
NOTE: 1R, 2R, and 4R in the following tables indicate single-, dual-, and quad-rank DIMMs.
Table 23. Memory configurations – two processors
System capacity (in
GB)
32
64
64
64
96
96
128
128
DIMM size (in Number of
GB) DIMMs
4 8
4 16
8 8
8 8
4 24
8 12
8 16
16 8
Memory population rules
{1,2}, {3,4}
Organization and
speed
1R x8, 2133 MT/s
1R x8, 2133 MT/s
1R x8, 2400 MT/s
2R x8, 2133 MT/s
1R x8, 2133 MT/s
2R x8, 2133 MT/s
1R x8, 2133 MT/s
2R x4, 2133 MT/s
Installing and removing sled components
Memory population information
See Memory mirroring note
DIMM slot population
A1, A2, A3, A4, B1, B2, B3, B4
A1, A2, A3, A4, A5, A6, A7, A8,
B1, B2, B3, B4, B5, B6, B7, B8
A1, A2, A3, A4, B1, B2, B3, B4
A1, A2, A3, A4, B1, B2, B3, B4
A1, A2, A3, A4, A5, A6, A7, A8,
A9, A10, A11, A12, B1, B2, B3, B4,
B5, B6, B7, B8, B9, B10, B11, B12
A1, A2, A3, A4, A5, A6, B1, B2,
B3, B4, B5, B6
A1, A2, A3, A4, A5, A6, A7, A8,
B1, B2, B3, B4, B5, B6, B7, B8
A1, A2, A3, A4, B1, B2, B3, B4
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