Dell PowerEdge VRTX - Manual (Page 33)

Advanced ECC (Lockstep)
Advanced ECC mode extends SDDC from x4 DRAM based DIMMs to both x4 and x8 DRAMs. This protects against single
DRAM chip failures during normal operation.
Memory installation guidelines:
• Memory sockets A1, A4, B1, and B4 are disabled and do not supported Advanced ECC mode.
• DIMMs must be installed in matched pairs — DIMMs installed in memory sockets (A2, B2) must match DIMMs
installed in memory sockets (A3, B3) and DIMMs installed in memory sockets (A5, B5) must match DIMMs
installed in memory sockets (A6, B6).
NOTE: Advanced ECC with mirroring is not supported.
Memory Optimized (Independent Channel) Mode
This mode supports SDDC only for memory modules that use x4 device width and does not impose any specific slot
population requirements.
Memory Sparing
NOTE: To use memory sparing, this feature must be enabled in the System Setup.
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 system with three 8 GB dual-rank DIMMs, the available system memory is: 1/2 (ranks/
channel) × 3 (DIMMs) × 8 GB = 12 GB, and not 3 (DIMMs) × 8 GB = 24 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.
Memory Mirroring
Memory Mirroring offers the strongest DIMM 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 DIMMs. In the event of an
uncorrectable error, the system will switch over to the mirrored copy. This ensures SDDC and multi-bit protection.
Memory installation guidelines:
NOTE: The first memory channel for each processor (Channel 1) is disabled and not available for Memory
Mirroring.
• Memory channels 2 and 3 must be populated.
• Memory modules must be identical in size, speed, and technology.
• DIMMs installed in memory sockets with white release tabs must be identical and similar rule applies for
sockets with black release tabs. For example, DIMMs installed in sockets A2 and A3 must be identical.
Sample Memory Configurations
The following tables show sample memory configurations that follow the appropriate memory guidelines stated in this
section.
NOTE: 16 GB quad-rank RDIMMs are not supported.
NOTE: 1R, 2R, and 4R in the following tables indicate single-, dual-, and quad-rank DIMMs respectively.
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