Dell EMC PowerEdge R740xd2 - Page 99

Table 9. Memory operating modes
Memory Operating Mode Description
Optimizer Mode The Optimizer Mode if enabled, the DRAM controllers operate
independently in the 64-bit mode and provide optimized memory
performance.
Mirror Mode The Mirror Mode if enabled, the system maintains two identical
copies of data in memory, and 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. This feature
provides maximum reliability and enables the system to continue
running even during a catastrophic memory failure by switching
over to the mirrored copy. The installation guidelines to enable
Mirror Mode require that the memory modules be identical in size,
speed, and technology, and they must be populated in sets of 6 per
processor.
Single Rank Spare Mode Single Rank Spare Mode allocates one rank per channel as a spare.
If excessive correctable errors occur in a rank or channel, while the
operating system is running, they are moved to the spare area to
prevent errors from causing an uncorrectable failure. Requires two
or more ranks to be populated in each channel.
Multi Rank Spare Mode Multi Rank Spare Mode allocates two ranks per channel as a spare.
If excessive correctable errors occur in a rank or channel, while the
operating system is running, they are moved to the spare area to
prevent errors from causing an uncorrectable failure. Requires three
or more ranks to be populated in each channel.
With single rank memory sparing enabled, the system memory
available to the operating system is reduced by one rank per
channel.
For example, in a dual-processor conguration with sixteen 16 GB
dual-rank memory modules, the available system memory: 16 GB x
16(memory modules) - 8GB(1 rank sparing/channel) x 12(channel) =
256 GB - 96 GB = 160 GB
For multi rank sparing, in a dual-processor conguration with
sixteen 64 GB quad-rank memory modules, the available system
memory: 64 GB x 16(memory modules) - 32 GB(2 rank sparing/
channel) x 12 (channel) = 1024 GB - 384 GB = 640 GB
NOTE: To use memory sparing, this feature must be
enabled in the BIOS menu of System Setup.
NOTE: Memory sparing does not oer protection against a
multi-bit uncorrectable error.
Optimizer Mode
This mode supports Single Device Data Correction (SDDC) only for memory modules that use x4 device width. It does not impose any
specic slot population requirements.
• Dual processor: Populate the slots in round robin sequence starting with processor 1.
Installing and removing system components
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