The server memory control subsystem selects a 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 the current DRAM technology supports 8 GB single-rank
DIMMs, a dual-rank DIMM can offer a capacity of 16 GB and a quad-rank DIMM can offer a
capacity of 32 GB.
LRDIMMs are labeled as quad-rank DIMMs. There are four 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. The LRDIMM buffer also isolates the electrical loading of
the DRAM from the system to allow for faster operation. These two changes provide a higher
memory operating speed compared with quad-rank RDIMMs.
6.2.3.4 DIMM Identification
To determine DIMM characteristics, see the label attached to the DIMM and refer to the
following figure and table.
Figure 6-3 DIMM identification
No.
Description Definition
1 Capacity
l 8 GB
l 16 GB
l 32 GB
l 64 GB
l 128 GB
2 Rank
l 1R: single-rank
l 2R: dual-rank
l 4R: quad-rank
3 Data width on DRAM
l X4: 4-bit
l X8: 8-bit
4 Memory generation
l PC3: DDR3
l PC4: DDR4
FusionServer G5500 Server
User Guide
6 Optional Part Installation
Issue 02 (2017-12-15) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
127
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