Dell PowerEdge C4140 EMC Installation and Service Manual - Page 77

Mode-specific guidelines

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• Unbalanced memory configurations will result in a performance loss so always populate memory channels identically with identical DIMMs for best performance. • Populate six identical memory modules per processor (one DIMM per channel) at a time to maximize performance. DIMM population update for Performance Optimized mode with quantity of 4 and 8 DIMMs per processor. • When the DIMM quantity is 4 per processor, the population is slot 1, 2, 4, 5. • When the DIMM quantity is 8 per processor, the population is slot 1, 2, 4, 5, 7, 8, 10, 11 (2-2-2 platforms). Mode-specific guidelines The configurations allowed depend on the memory mode selected in the System BIOS. Table 34. Memory operating modes Memory Operating Mode Optimizer Mode Description The Optimizer Mode if enabled, the DRAM controllers operate independently in the 64-bit mode and provide optimized memory performance. Mirror Mode Single Rank Spare Mode Multi Rank Spare 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 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. 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. NOTE: This feature is only supported in Gold and Platinum Intel processors. PowerEdge C4140 installing and removing system components 77

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Unbalanced memory configurations will result in a performance loss so always populate memory channels identically with identical
DIMMs for best performance.
•
Populate six identical memory modules per processor (one DIMM per channel) at a time to maximize performance.
DIMM population update for Performance Optimized mode with quantity of 4 and 8 DIMMs per processor.
•
When the DIMM quantity is 4 per processor, the population is slot 1, 2, 4, 5.
•
When the DIMM quantity is 8 per processor, the population is slot 1, 2, 4, 5, 7, 8, 10, 11 (2-2-2 platforms).
Mode-specific guidelines
The configurations allowed depend on the memory mode selected in the System BIOS.
Table 34. 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 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.
NOTE:
This feature is only supported in Gold and
Platinum Intel processors.
PowerEdge C4140 installing and removing system components
77