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Configuration 3. Four-Socket Upgradable

The ThinkSystem SR950 is available in several configurations.

The lowest-cost 4-socket server capable of a simple upgrade to 8 socket and when 12 drive bays with 4 processors is enough storage.

  • 2 or 4 processors, must be 8100 Series processors

  • 4 processors in a ring topology

  • 12 drive bays including up to 6 NVMe (2 NVMe with 2 processors)

  • Up to 15 rear PCIe slots with 4 processors (6 rear slots with 2 processors)

  • Filler installed in the upper tray area

  • Upgradable to 8-socket with an additional compute tray and two system boards

  • Once upgraded, the system will have 24 drive bays

Processor configurations

This configuration supports 2, 3, or 4 processors.
  • 2-processor configuration. Processors are installed in location 1 and 2.

  • 4-processor configuration. Processors are installed in locations 1, 2, 3, and 4.

Figure 1. Processor numbering (viewed from the front of the server)
CPU and DIMM layout for multiple-processor systems

PCIe slot connectivity

The following table shows the processor to PCIe slot connectivity:
PCIe slotSlot locationDescription
1Riser 1


Not connected for 2x16. Slots 1 and 2 are not connected if the 2x16 riser is used in riser slot 1



Not connected for 2x16. Slots 1 and 2 are not connected if the 2x16 riser is used in riser slot 1





5I/O tray2
8 (ML2)1
9 (LOM)1 (PCH)
10Riser 232
14Not connected.
15 (ML2)Not connected.
162x8 Riser32
M.2I/O tray1 (PCH)
Storage adapterUpper trayNot connected.
Storage adapterLower tray1
  1. In 2-processor configurations, processors 3 and 4 are not installed; this means slots 1-4, slot 10-13, and slot 16 are not connected

  2. In 3-processor configurations, processor 3 is not installed; this means slot 10-13, and slot 16 are not connected

Drive bays

Drives are all located at the front of the server, 12 drives at the front of the upper tray and 12 at the front of the lower tray. Drives are connected to 4-drive backplanes in a 2-by-2 configuration, as shown in the following figure. All drive bays are 2.5-inch form factor.

Two different drive backplanes are available for the server:
  • SAS/SATA backplane: Supports 4 SAS or SATA drives

  • AnyBay backplane:

    • Top two drives support SAS, SATA, or NVMe interface drives (Lenovo AnyBay). The server can support up to 12 NVMe drives, depending on the server configuration. The NVMe-capable drive bays are the even-numbered bays as shown in Figure 2.

    • Bottom two drive bays support SAS or SATA drives only

Regular 2.5-inch SAS/SATA drive bays support only SAS or SATA drives; however, the Lenovo AnyBay drive bay design allows a choice of SATA, SAS, or U.2 (NVMe) PCIe drives. This design enables the flexibility to configure some of the bays with high-performance PCIe SSDs while still using the other bays for high-capacity HDDs, which is an ideal solution for storage-tiering.

Figure 2. Drive bay locations

The following table lists the drive bays and NVMe support for the Four-Socket Performance configuration.
Installed processorsMaximum storageLocation of NVMe drives (see Figure 2)
212 drives (2 NVMe drives)Bays 8 and 10
412 drives (6 NVMe drives)Bays 0, 2, 4, 6, 8, 10