Memory Subsystem Architecture; Dimm Ranks; Identifying Dimm And Nvdimms - HP ProLiant DL360 Gen9 User Manual

Memory subsystem architecture

The memory subsystem in this server is divided into channels. Each processor supports four channels,
and each channel supports three DIMM slots, as shown in the following table.
Channel
1
2
3
4
For the location of the slot numbers, see "DIMM slot locations
This multi-channel architecture provides enhanced performance in Advanced ECC mode. This
architecture also enables Online Spare Memory mode.
DIMM slots in this server are identified by number and by letter. Letters identify the population order. Slot
numbers indicate the DIMM slot ID for spare replacement.
For more information about NVDIMM-Ns and persistent memory, see the HPE 8GB NVDIMM User Guide
on the Hewlett Packard Enterprise Information Library (http://www.hpe.com/info/NVDIMM-docs).

DIMM ranks

To understand and configure memory protection modes properly, an understanding of DIMM rank is
helpful. Some DIMM configuration requirements are based on these classifications.
A single-rank DIMM has one set of memory chips that is accessed while writing to or reading from the
memory. A dual-rank DIMM is similar to having two single-rank DIMMs on the same module, with only one
rank accessible at a time. A quad-rank DIMM is, effectively, two dual-rank DIMMs on the same module.
Only one rank is accessible at a time. The server memory control subsystem selects the proper rank
within the DIMM when writing to or reading from the DIMM.
Dual- and quad-rank DIMMs provide the greatest capacity with the existing memory technology. For
example, if current DRAM technology supports 8-GB single-rank DIMMs, a dual-rank DIMM would be 16
GB, and a quad-rank DIMM would be 32 GB, and an octal-rank LRDIMM would be 64 GB.
LRDIMMs are labeled as quad- and octal-rank DIMMs. There are four and eight ranks of DRAM on the
DIMM, but the LRDIMM buffer creates an abstraction that allows the DIMM to appear as a logical
dual-rank DIMM to the system. This is called Rank Multiplication. The LRDIMM buffer also isolates the
electrical loading of the DRAM from the system to allow for faster operation. These two changes allow the
system to support up to three LRDIMMs per memory channel, providing for greater memory capacity and
higher memory operating speed compared to quad-rank RDIMMs.

Identifying DIMM and NVDIMMs

DIMMs and NVDIMMs are visibly different and contain different information on the label.
Population order
A
E
I
B
F
J
C
G
K
D
H
L
Slot number
12
11
10
9
8
7
1
2
3
4
5
6
("DIMM slots" on page 16)."
Hardware options installation 45