Memory Options - Lenovo ThinkSystem SN550 Product Manual

Memory options

The SN550 uses Lenovo TruDDR4 memory operating at speeds up to 2666 MHz. All DIMMs can operate
at a speed of 2666 MHz, both at 1 DIMM per channel and 2 DIMMs per channel. However, if the processor
selected has a lower memory bus speed (eg 2400 MHz), then all DIMMs will operate at that lower speed.
TruDDR4 Memory uses the highest quality components that are sourced from Tier 1 DRAM suppliers and
only memory that meets the strict requirements of Lenovo is selected. It is compatibility tested and tuned
on every ThinkSystem server to maximize performance and reliability. TruDDR4 Memory has a unique
signature that is programmed into the DIMM that enables ThinkSystem servers to verify whether the
memory that is installed is qualified and supported by Lenovo.
From a service and support standpoint, Lenovo TruDDR4 memory automatically assumes the Lenovo
system warranty and Lenovo provides service and support worldwide.
The following table lists the memory options that are available for the SN550 server.
Table 14. Memory options
Part Feature
number code
RDIMMs
7X77A01301 AUU1
7X77A01302 AUNB
7X77A01303 AUNC
7X77A01304 AUND
LRDIMMs
7X77A01305 AUNE
The following rules apply when selecting the memory configuration:
The server supports RDIMMs and LRDIMMs. UDIMMs are not supported.
Mixing RDIMMs and LRDIMMs is not supported.
Mixing x4 and x8 DIMMs is supported.
For best performance, populate memory DIMMs in quantities of 6 or 12 per processor, so that all
memory channels are used.
The following memory protection technologies are supported:
ECC
SDDC (for x4-based memory DIMMs; look for "x4" in the DIMM description)
Memory channel mirroring
Memory rank sparing
If memory channel mirroring is used, then DIMMs must be installed in pairs or sets of three (minimum of
one pair or set of three per processor), and all DIMMs in the pair or set of three must be identical in type
and size. 50% of the installed capacity is available to the operating system.
If memory rank sparing is used, then a minimum of one quad-rank DIMM or two single-rank or dual-rank
DIMMs must be installed per populated channel (the DIMMs do not need to be identical). In rank sparing
mode, one rank of a DIMM in each populated channel is reserved as spare memory. The largest rank in
the channel will be automatically selected as the spare rank. The amount of memory available to the
operating system depends on the number, capacity and rank counts of the DIMMs installed.
Lenovo ThinkSystem SN550 Server
Description
ThinkSystem 8GB TruDDR4 2666 MHz (1Rx8 1.2V) RDIMM
ThinkSystem 16GB TruDDR4 2666 MHz (1Rx4 1.2V) RDIMM
ThinkSystem 16GB TruDDR4 2666 MHz (2Rx8 1.2V) RDIMM
ThinkSystem 32GB TruDDR4 2666 MHz (2Rx4 1.2V) RDIMM
ThinkSystem 64GB TruDDR4 2666 MHz (4Rx4 1.2V) LRDIMM
Maximum
supported
24 (12 per processor)
24 (12 per processor)
24 (12 per processor)
24 (12 per processor)
24 (12 per processor)
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