Mirroring mode installation order
Mirroring mode provides full memory redundancy while reducing the total system memory capacity in half. Memory channels are grouped in pairs with each channel receiving the same data. If a failure occurs, the memory controller switches from the DIMMs on the primary channel to the DIMMs on the backup channel. The DIMM installation order for memory mirroring varies based on the number of processors and DIMMs installed in the server.
In mirroring mode, each memory module in a pair must be identical in size and architecture. The channels are grouped in pairs with each channel receiving the same data. One channel is used as a backup of the other, which provides redundancy.
All memory modules to be installed must be of the same Lenovo part number.
Partial Memory Mirroring is a sub-function of memory mirroring. It requires following the memory installation order of memory mirroring mode.
The following table shows the DIMM installation order for mirroring mode when only one processor (processor 1) is installed.
| Total DIMMs | Processor 1 | ||||||||||||||||
| 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | ||
| 8 DIMMs | 16 | 14 | 12 | 10 | 7 | 5 | 3 | 1 | |||||||||
| 16 DIMMs | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
The following table shows the DIMM installation order for mirroring mode when two processors are installed.
| Total DIMMs | Processor 1 | ||||||||||||||||
| 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | ||
| 16 DIMMs | 16 | 14 | 12 | 10 | 7 | 5 | 3 | 1 | |||||||||
| 32 DIMMs | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| Total DIMMs | Processor 2 | ||||||||||||||||
| 32 | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | ||
| 16 DIMMs | 32 | 30 | 28 | 26 | 23 | 21 | 19 | 17 | |||||||||
| 32 DIMMs | 32 | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | |
All DIMM configurations in mirroring mode support the Sub NUMA Clustering (SNC) feature, which can be enabled via UEFI.
- Supported DIMMs are subject to the following restrictions:
DIMM configuration Slot No. Supported DIMMs 8-DIMM (1P) or 16-DIMM (2P) 0 16/32/48/64/96/128 GB RDIMMs, 32/64 GB MRDIMMs, or 256 GB 3DS RDIMMs 1 N/A 16-DIMM (1P) or 32-DIMM (2P) 0 32 GB (2Rx8), 64 GB, 96 GB, or 128 GB RDIMMs or 256 GB 3DS RDIMMs 1 Same as slot 0 1P: one processor; 2P: two processors