Owners Manual

Table 38. Memory operating modes (continued)
Memory Operating Mode Description
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 configuration with 24x 16 GB
dual-rank memory modules, the available system memory is:
3/4 (ranks/channel) × 24 (memory modules) × 16 GB = 288
GB, and not 24 (memory modules) × 16 GB = 384 GB.
For multi rank sparing, the multiplier changes to 1/2 (ranks/
channel).
NOTE: To use memory sparing, this feature must be
enabled in the BIOS menu of System Setup.
NOTE: Memory sparing does not offer protection against
a multi-bit uncorrectable error.
Dell Fault Resilient Mode The Dell Fault Resilient Mode if enabled, the BIOS creates
an area of memory that is fault resilient. This mode can be
used by an OS that supports the feature to load critical
applications or enables the OS kernel to maximize system
availability.
Optimizer Mode
This mode supports Single Device Data Correction (SDDC) only for memory modules that use x4 device width. It does not
impose any specific slot population requirements.
● Dual processor: Populate the slots in round robin sequence starting with processor 1.
NOTE: Processor 1 and processor 2 population should match.
Table 39. Memory population rules
Processor Configuration Memory population Memory population information
Single processor Optimizer (Independent
channel) population order
1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
11, 12
● DIMMs must be populated in the order
specified.
● Odd number of DIMM population is allowed
NOTE: Odd number of DIMMs will result
in unbalanced memory configurations,
which in turn will result in performance
loss. It is recommended to populate
80 Installing and removing system components