Penguin Computing Relion 1900e, Technical Manual

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Relion 1900e/2900e Manual
Revision 1.0 28
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Independent Channel mode: In Independent Channel Mode, the amount of installed physical
memory is the amount of effective memory available. There is no reduction.

Lockstep Mode: For Lockstep Mode, the amount of installed physical memory is the amount of
effective memory available. There is no reduction. Lockstep Mode only changes the addressing to
address two channels in parallel.

Rank Sparing Mode: In Rank Sparing mode, the largest rank on each channel is reserved as a spare
rank for that channel. This reduces the available memory size by the sum of the sizes of the reserved
ranks.
Example: if a system has 2 16GB Quad Rank DIMMS on each of 4 channels on each of 2 processor
sockets, the total installed memory will be (((2 * 16GB) * 4 channels) * 2 CPU sockets) = 256GB.
For a 16GB QR DIMM, each rank would be 4GB. With one rank reserved on each channel, that would
32GB reserved. So the available effective memory size would be 256GB - 32GB, or 224GB.

Mirroring Mode: Mirroring creates a duplicate image of the memory that is in use, which uses half of
the available memory to mirror the other half. This reduces the available memory size to half of the
installed physical memory.
Example: if a system has 2 16GB Quad Rank DIMMS on each of 4 channels on each of 2 processor
sockets, the total installed memory will be (((2 * 16GB) * 4 channels) * 2 CPU sockets) = 256GB.
In Mirroring Mode, since half of the memory is reserved as a mirror image, the available memory size
would be 128GB.
4.7.2 Publishing System Memory
There are a number of different situations in which the memory size and/or configuration are displayed.
Most of these displays differ in one way or another, so the same memory configuration may appear to
display differently, depending on when and where the display occurs.

The BIOS displays the “Total Memory” of the system during POST if Quiet Boot is disabled in BIOS
setup. This is the total size of memory discovered by the BIOS during POST, and is the sum of the
individual sizes of installed DDR4 DIMMs in the system.

The BIOS displays the “Effective Memory” of the system in the BIOS Setup. The term Effective
Memory refers to the total size of all DDR4 DIMMs that are active (not disabled) and not used as
redundant units (see Note below).

The BIOS provides the total memory of the system in the main page of BIOS setup. This total is the
same as the amount described by the first bullet above.

If Quiet Boot is disabled, the BIOS displays the total system memory on the diagnostic screen at the
end of POST. This total is the same as the amount described by the first bullet above.

The BIOS provides the total amount of memory in the system by supporting the EFI Boot Service
function, GetMemoryMap().

The BIOS provides the total amount of memory in the system by supporting the INT 15h, E820h
function. For details, see the Advanced Configuration and Power Interface Specification.
Note: Some server operating systems do not display the total physical memory installed. What is displayed is
the amount of physical memory minus the approximate memory space used by system BIOS components.
These BIOS components include but are not limited to:

ACPI (may vary depending on the number of PCI devices detected in the system and the size of
memory included on them)

ACPI NVS table

Processor microcode