EDSFF E1.S Form Factor

KIOXIA Corporation provides next-generation PCIe® 4.0 data center NVMe™ SSDs with its XD6 Series, which are designed to the Open Compute Project® (OCP) NVMe™ Cloud SSD specification and available in E1.S form factors. There are a number of key reasons why these new EDSFF E1.S SSDs can enable a data center server architecture to adapt to changes, but the top five supported by KIOXIA include:

Higher Performance / Higher Power Budget vs. M.2 Devices: More than doubles the power budget versus M.2 devices, enabling E1.S SSDs to saturate PCIe® Gen4 performance.

Standardized Thermal Solutions: Improves interoperability across vendors and platforms while providing the flexibility to select the right balance of cooling and storage density through different E1.S heatsink options.

Improved Physical Serviceability: Vastly improves serviceability with hot plug support that no longer requires an entire server to be taken down in order to replace a single SSD.

Designed to Better Accommodate NAND Flash Memory Packages: Wider PCB design enables optimized orientation of the NAND flash memory packages, providing headroom for higher capacity drives.

Supported by Leading Hyperscalers: Meta™ and Microsoft®, leading authors of the OCP NVMe™ Cloud SSD specification, are specifying E1.S designs on upcoming OCP platforms, promoting industry-wide adoption.

The Benefits of E1 EDSFF


EDSFF connector design and placement is the same standard across all EDSFF configurations, allowing for flexible chassis and backplane design


EDSFF can reach up to 40W for per device superior performance, while the SFF-8639 connector (used in 2.5” SSDs) can only reliably supply up to 25W

4x Performance

EDSFF can support up to 4x higher performance in a 4C configuration with 16 PCIe lanes than a 4 lane U.2 or U.3 compliant 2.5” SSD

Future Proof

The EDSFF connector is designed to handle PCIe® 5.0 frequencies and PCIe 6.0 while U.2 is limited to PCIe 5.0 and U.3 is limited to PCIe 4.0


The EDSFF is designed with efficient use of space and surface area, improving thermal dissipation and allowing for higher density chassis


EDSFF is designed to be used with other PCIe applications like networking or compute peripherals, not limited to SSDs

E1 - Hyperscale Servers and Storage

E1 EDSFF size and dimension E1 EDSFF size and dimension
Type Width Length Height (Thickness) Max Power
E1.S 5.9mm 31.5 mm 111.49 mm 5.9 mm 12W
E1.S 8 mm Heat Spreader 8.01 mm
E1.S 9.5 mm Symmetric Enclosure 33.75 mm 118.75 mm 9.5 mm 25W
E1.S 15 mm Asymmetric Enclosure 15 mm
E1.S 25 mm Asymmetric Enclosure 25 mm
E1.L 9.5 mm 38.4 mm 318.75 9.5 mm
E1.S 18 mm 18 mm 40W

E1.S EDSFF Use Cases

E1.S form factors are well-suited for these use cases:

E1.S 9.5 mm

Target System Small footprint systems
Examples Blade servers; Edge compute and storage systems; Dense, scaled servers
Primary Need(s) Performance; Excellent thermal capabilities
Use(s) U.2 and M.2 replacement
Typical Configuration 6 to 12 E1.S SSDs
A server rack with E1.S 9.5mm

E1.S 15 mm

Target System 1U/2U/4U and special-purpose systems
Examples Compute blades and systems; Performance and capacity-optimized storage systems; Artificial Intelligence/Machine Learning (AI/ML) and High Performance Computing (HPC) systems; Edge systems
Primary Need(s) Scalable performance and capacity; Optimized thermal performance
Use(s) U.2 and M.2 replacement for boot and primary storage
Typical Configuration 2 to 32 E1.S SSDs
A server rack with E1.S 15 mm

E1.S 25 mm

Target System 2U and larger systems
Examples Storage appliances; Input/Output (I/O) and storage-rich servers / databases; Performance-oriented storage systems
Primary Need(s) Scalability of performance with capacity; Lower cost per performance
Use(s) Mainstream U.2 replacement
Typical Configuration 36 to 64 E1.S SSDs
A server rack with E1.S 25 mm


XD6 E1.S

KIOXIA XD6 E1.S 9.5mm, 15mm, and 25mm product image


KIOXIA XD7P E1.S 9.5mm, 15mm, and 25mm product image

Benefits of E1

  • E1 form factor delivers better thermal dissipation versus M.2 form factors
  • E1 SSDs enable higher density storage and better thermal management in 1U chassis
  • E1 form factor allows for higher power delivery up to 40W versus M.2
Product Form Factor Endurance Interface Storage Capacity (GB) Sequential Read/Write Random Read/Write
XD6 EDSFF E1.S Read Intensive
(1 DWPD for 5 years)
PCIe® 4.0, NVMe™ 1.3c 1,920
Up to
6,500/2,400 MB/s
Up to
850K/90K IOPS
XD7P Designed to PCIe® 5.0
and NVMe™ 1.4 
Up to
7,100/4,800 MB/s
Up to
1,500K/170K IOPS

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Additional Resources