Removing A Memory Module - Dell EMC PowerEdge R940 Installation And Service Manual

Table 25. Memory operating modes (continued)
Memory Operating Mode
Single Rank Spare Mode
Multi Rank Spare Mode
Dell Fault Resilient Mode
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.
● Quad processor: Populate the slots in round robin sequence starting with processor 1.
NOTE: Processor 1, processor 2, processor 3, and processor 4 population should match.

Removing a memory module

The procedure for removing a DIMM module and an NVDIMM-N module is identical.
Prerequisites
1. Follow the safety guidelines listed in
2. Follow the procedure listed in
CAUTION: To prevent data loss and potential damage to your system, ensure that your system, LEDs on
system, LEDs on NVDIMM-N and LEDs on NVDIMM-N battery are turned off before removing the NVDIMM-N
battery.
3. Remove the air shroud.
Description
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 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.
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.
NOTE: This feature is only supported in Gold and Platinum Intel processors.
NOTE: Memory configuration has to be of same size DIMM, speed, and rank.
Safety instructions
Before working inside your system
on page 29.
on page 30.
Installing and removing system components 73