Dell Unity XT Unity 400
The Dell EMC Unity 400 is a mid-tier hybrid storage array from the initial Unity generation, offering expanded processing power and memory over the entry Unity 300. Powered by dual active-active Storage Processors with 96GB of RAM and 16 Intel Xeon cores, the Unity 400 scales up to 250 drives and 1.5PB of raw capacity. It natively serves concurrent block (Fibre Channel, iSCSI) and file (NFS, SMB) workloads, utilizing FAST VP auto-tiering to optimize data placement across SAS SSD and HDD tiers. A common fixture on the secondary market, buyers should test lithium-ion backup batteries and confirm installed drive firmware.
Also written as: Dell EMC Unity 400, Unity 400 Hybrid
Specifications
| Brand | Dell |
|---|---|
| Family | Unity XT |
| Form factor | 2U rack |
| Released | May 2016 |
| End of sale | Jan 2020 |
| End of support | Jan 2025 |
| Cpu platform | Dual active-active storage processors (SPs), Intel Xeon E5-2600 v3 8-core (2.4 GHz) per SP |
| Memory max (GB) | 96 |
| Drive bays | Up to 25x 2.5-inch drives in base DPE; expands up to 250 drives across SAS DAEs |
| Raw capacity | Up to 1.5 PB raw capacity |
| Network onboard | 4-port 10GbE / 1GbE Base-T; 2x I/O module slots per SP supporting 8Gb/16Gb FC or 10GbE optical |
| Power supply | Dual redundant hot-plug 800W Platinum power supplies |
Generations
- Previous generation: Dell Emc VNX5400
- Next generation: Dell Unity XT 480XT
Works together
How the Dell Unity XT Unity 400 connects to servers, storage and the network: 3 ways, with the parts and products on each path.
Fibre Channel SAN
Match the speed: 16Gb and 32Gb FC HBAs, switches and array ports work together, and each generation also runs one or two speeds below its own (a 32Gb port runs at 16Gb and 8Gb).
Servers
Dell PowerEdge R640 1U rack
Dell PowerEdge R740 2U rack
Dell PowerEdge R730 2U rack
Dell PowerEdge R660 1U rack
Dell PowerEdge R760 2U rack
Dell PowerEdge R830 2U rack
Adapters for the server
540-BBUU Dell Emulex LPe31002 Dual Port 16Gb Fibre Channel Host Bus Adapter
540-BBUV Dell QLogic 2692 Dual Port 16Gb Fibre Channel Host Bus Adapter
540-BCMT Dell QLogic 2772 Dual Port 32Gb Fibre Channel PCIe Adapter
540-BCMU Dell Emulex LPe35002 Dual Port 32Gb Fibre Channel PCIe Adapter
Switches
Dell Connectrix DS-6620B 1U rack
Dell Connectrix DS-6610B 1U rack
Dell Connectrix MDS-9148T 1U rack
Dell Connectrix DS-7720B 1U rack
Optics
iSCSI and NVMe/TCP over Ethernet
Keep the speed the same at all three points: a 25GbE server, a 25GbE switch port and a 25GbE array port. Mixed speeds work but the slowest link sets the pace.
Servers
- Dell PowerEdge R640 1U rack
- Dell PowerEdge R740 2U rack
- Dell PowerEdge R730 2U rack
Dell PowerEdge R650 1U rack
Dell PowerEdge R750 2U rack- Dell PowerEdge R660 1U rack
Adapters for the server
540-BBGO Dell Broadcom 57416 Dual Port 10GBASE-T RJ45 PCIe Adapter
540-BBGY Dell Broadcom 57414 Dual Port 10/25GbE SFP28 PCIe Low Profile Network Adapter
540-BBHB Dell Broadcom 57414 Dual Port 10/25GbE SFP28 OCP 3.0 Mezzanine Network Adapter
540-BBRL Dell Intel X710 Quad Port 10GbE SFP+ Full-Height PCIe Adapter
Switches
Dell PowerSwitch S4148F-ON 1U rack
Dell PowerSwitch S5248F-ON 1U rack
Dell PowerSwitch S4128F-ON 1U rack
Dell PowerSwitch S4112F-ON 1U rack
Optics
407-BBOU Dell 10GbE SFP+ SR Optical Transceiver (850nm, 300m MMF)
407-BCBF Dell 25GbE SFP28 SR Optical Transceiver (850nm, 100m MMF)
SFP-10G-SR-AR Arista 10GBASE-SR SFP+ Optical Transceiver
File storage (NFS and SMB)
Front-end ports face the clients; back-end ports (on scale-out systems) connect the nodes to each other and need their own switch pair.
Servers
- Dell PowerEdge R640 1U rack
- Dell PowerEdge R740 2U rack
- Dell PowerEdge R730 2U rack
- Dell PowerEdge R650 1U rack
- Dell PowerEdge R750 2U rack
- Dell PowerEdge R660 1U rack
Adapters for the server
- 540-BBGO Dell Broadcom 57416 Dual Port 10GBASE-T RJ45 PCIe Adapter
- 540-BBGY Dell Broadcom 57414 Dual Port 10/25GbE SFP28 PCIe Low Profile Network Adapter
- 540-BBHB Dell Broadcom 57414 Dual Port 10/25GbE SFP28 OCP 3.0 Mezzanine Network Adapter
- 540-BBRL Dell Intel X710 Quad Port 10GbE SFP+ Full-Height PCIe Adapter
Switches
- Dell PowerSwitch S4148F-ON 1U rack
- Dell PowerSwitch S5248F-ON 1U rack
- Dell PowerSwitch S4128F-ON 1U rack
- Dell PowerSwitch S4112F-ON 1U rack
Optics
- 407-BBOU Dell 10GbE SFP+ SR Optical Transceiver (850nm, 300m MMF)
- 407-BCBF Dell 25GbE SFP28 SR Optical Transceiver (850nm, 100m MMF)
- SFP-10G-SR-AR Arista 10GBASE-SR SFP+ Optical Transceiver
Plan and size it
- Draw this setup in the topology planner mrplanb.com
- Add up rack power and space rack-density.com
- Virtualization storage Ledger: scored storage platforms mrplanb.com
- SAN transport and NVMe over FC for backup mrplanb.com
- Dell E-Lab Navigator (Dell interoperability) dell.com
Check compatibility with Dell
Before you buy, confirm the exact configuration against the vendor's own lists: firmware levels, operating systems, adapters and optics that Dell has tested with the Dell Unity XT Unity 400.
- Compatibility Dell E-Lab Navigator (storage and SAN interoperability) (free vendor sign-in)
- Support Dell Support: drivers, manuals and service tag lookup
Equivalent models from other brands
- NetApp FAS2650
- HPE Alletra 5000 · compare
Buying a used Unity 400: what to check
Inspect internal BBU lithium-ion battery packs on both SPs, confirm that installed drives carry Dell Unity firmware, and verify 16Gb FC or 10GbE SFP+ optics.
FAQ
What is the memory footprint of the Unity 400?
96GB total system RAM across dual Storage Processors (48GB per SP).
How many drives can the Unity 400 support?
Up to 250 drives supporting up to 1.5 PB of raw capacity across expansion shelves.
Buying or selling Unity 400?
New, refurbished or used. Tell us the quantity and condition and we connect you with a vetted reseller in your region, usually within one working day.
Sources
- Dell EMC Unity 400 Spec Sheet, checked 2026-10-27