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EDSFF E3.S is the storage form factor built for PCIe Gen5 NVMe — denser, cooler, and faster than the 2.5-inch drives it's replacing. Here's what it is, how it compares to U.2/U.3, and which HPE ProLiant servers use it.
Last updated: 2026
EDSFF (Enterprise and Datacenter Standard Form Factor) E3.S is the storage industry's purpose-built shape for NVMe SSDs in modern servers. Defined by SNIA to move beyond the aging 2.5-inch (U.2/U.3) and add-in-card formats, it's engineered around the realities of PCIe Gen5 and beyond: higher density, better airflow, and a larger power budget. On HPE ProLiant servers, EDSFF E3.S is the high-density NVMe option on Gen11 and Gen12. Here's what sets it apart and how to deploy it.
What is EDSFF E3.S?
EDSFF is a family of SSD form factors standardized by SNIA (the Storage Networking Industry Association) specifically for data center NVMe storage. The E3 family is the one built for mainstream enterprise rack servers, and it comes in a few variants:
| Variant | Dimensions (H × L × T) | Notes |
|---|---|---|
| E3.S | 76 × 112.75 × 7.5 mm | Mainstream high-density NVMe — the variant HPE uses most |
| E3.S 2T | 76 × 112.75 × 16.8 mm | Double-thick for higher-capacity, higher-power drives |
| E3.L | 76 × 142.2 × 7.5 mm | Long format for greater capacity per drive |
| E3.L 2T | 76 × 142.2 × 16.8 mm | Long and double-thick for the highest capacity and power |
In the naming, S is the short length and L is the long length, while 2T means double-thickness (16.8 mm instead of 7.5 mm) for more NAND and a higher power budget. E3.S is the most common variant and the one HPE uses across its NVMe-dense Gen11 and Gen12 servers. All variants connect through the EDSFF edge connector (SFF-TA-1009), which can carry up to PCIe x16 lanes, though mainstream NVMe SSDs use a x4 link.
Why EDSFF replaced the 2.5-inch drive
The 2.5-inch SFF drive and its U.2/U.3 connector served NVMe well through PCIe Gen3 and Gen4, but it was never designed for the heat and density of Gen5 and beyond. EDSFF E3.S was built from the ground up to solve that:
- Density — the thin, tall E3.S profile lets a server pack more drives into the same chassis: up to 36 E3.S SSDs in a 2U DL380 Gen11, versus 24 in 2.5-inch.
- Thermals — the form factor is shaped for straight-through airflow, so high-power Gen5 drives stay cool without throttling, a growing problem for hot NVMe drives in 2.5-inch bays.
- Scalable power — where 2.5-inch tops out around 25W, EDSFF scales from roughly 25W (E3.S) to about 40W (E3.S 2T) and higher on the long variants, leaving headroom for faster controllers and denser NAND.
- Serviceability — E3.S drives are front-loading and hot-pluggable, like 2.5-inch, so they keep the tool-less, swap-in-place service model data centers rely on.
| Attribute | 2.5-inch SFF (U.2/U.3) | EDSFF E3.S |
|---|---|---|
| Connector | SFF-8639 | SFF-TA-1009 (EDSFF) |
| PCIe | Up to Gen4 x4 | Gen5 x4 (connector supports up to x16) |
| Drive density | Moderate | High |
| Power budget | Up to ~25W | ~25W (E3.S) to ~40W (E3.S 2T) |
| Thermals | Adequate through Gen4 | Designed for Gen5 and beyond |
| Hot-plug | Yes | Yes |
| Best for | Mixed SAS / SATA / NVMe fleets | High-density, high-performance NVMe |
Performance: built for PCIe Gen5 NVMe
E3.S drives connect over NVMe via PCIe Gen5, roughly doubling the bandwidth of Gen4. A single Gen5 enterprise E3.S SSD can reach throughput on the order of 14 GB/s and millions of IOPS, with the very low latency NVMe is known for — microseconds, not milliseconds. For workloads bottlenecked on storage — large-scale analytics, AI/ML training and inference, in-memory and transactional databases, and high-performance virtualization — that bandwidth and parallelism translate directly into faster results and higher consolidation ratios.
Reliability and endurance
Like all enterprise SSDs, HPE E3.S drives include the data-protection features that separate data center storage from consumer drives: power-loss protection (onboard capacitors plus firmware that finishes in-flight writes when power drops), end-to-end data-path protection, and advanced ECC such as LDPC that corrects NAND bit errors before they reach your data. Endurance is rated in Drive Writes Per Day (DWPD) and grouped into Read Intensive (around 1 DWPD), Mixed Use (around 3 DWPD), and Write Intensive (around 10 DWPD) classes — match the class to your workload. On genuine HPE drives, the SmartSSD Wear Gauge reports remaining endurance through iLO so you can plan replacements before a drive wears out, and firmware is digitally signed for supply-chain security.
EDSFF E3.S on HPE ProLiant servers
On HPE, E3.S is the high-density NVMe option introduced with Gen11 and carried into Gen12. It requires a server configured with an EDSFF drive cage, and E3.S drives use their own EDSFF carrier — they don't share the Basic Carrier used by 2.5-inch SFF drives. Representative Gen11 capacities:
- DL360 Gen11 (1U) — up to 20 E3.S NVMe SSDs
- DL380 Gen11 (2U) — up to 36 E3.S NVMe SSDs
- ML350 Gen11 (tower) — up to 12 E3.S NVMe SSDs
Because E3.S is a different physical format with a different connector, an E3.S drive can't go into a 2.5-inch U.2/U.3 bay, and a 2.5-inch drive can't go into an EDSFF cage. The server has to be built with EDSFF cages from the start. If you're not sure how your server is configured, check its QuickSpecs or send us the model and we'll confirm.
E3.S vs U.3 vs 2.5-inch: which should you choose?
- Choose EDSFF E3.S for maximum NVMe density and Gen5 performance on a Gen11 or Gen12 server built for it — ideal for AI, analytics, and storage-dense flash.
- Choose 2.5-inch U.3 for flexibility: tri-mode bays run SAS, SATA, or NVMe in the same slots, which suits mixed fleets and gradual NVMe adoption. See our guide to U.2 vs U.3 SSDs.
- Choose 2.5-inch SAS/SATA when capacity per dollar or compatibility with existing drives matters more than peak NVMe speed.
In practice the server makes the decision: if it has EDSFF cages, E3.S is the high-density path; if it has tri-mode SFF bays, U.3 is the flexible one.
Where to buy HPE EDSFF E3.S SSDs
Shop by interface, then filter by capacity and endurance:
- HPE EDSFF E3.S NVMe SSDs — high-density NVMe for Gen11 / Gen12
- HPE U.3 NVMe SSDs — tri-mode 2.5-inch bays
- All HPE server SSDs
Not sure whether your server supports EDSFF? Contact us with your model or serial number and we'll confirm the right drive and cage before you order.
Frequently asked questions
What is EDSFF E3.S?
EDSFF (Enterprise and Datacenter Standard Form Factor) E3.S is a storage form factor standardized by SNIA for data center NVMe SSDs. It was designed to move beyond the 2.5-inch (U.2/U.3) format with higher density, better airflow, and a larger power budget suited to PCIe Gen5 and newer drives.
How is E3.S different from a 2.5-inch U.2/U.3 SSD?
Both are hot-pluggable NVMe SSDs, but E3.S uses a different physical shape and the EDSFF (SFF-TA-1009) connector instead of the 2.5-inch SFF-8639. E3.S packs more drives per chassis, handles more power, and is shaped for the airflow that high-performance PCIe Gen5 drives need. A 2.5-inch U.3 bay and an E3.S bay are not interchangeable.
What do E3.S, E3.L, and 2T mean?
Within the EDSFF E3 family, S is the short length (112.75 mm) and L is the long length (142.2 mm), while 2T means double-thickness (16.8 mm instead of 7.5 mm) for more NAND capacity and a higher power budget. E3.S is the mainstream variant HPE uses on its NVMe-dense Gen11 and Gen12 servers.
Which HPE ProLiant servers support EDSFF E3.S?
E3.S was introduced on HPE ProLiant Gen11 and continues on Gen12, on servers configured with EDSFF drive cages. On Gen11, for example, the DL360 supports up to 20 E3.S SSDs, the DL380 up to 36, and the ML350 up to 12. The server must be ordered with EDSFF cages, because E3.S drives don't fit standard 2.5-inch bays.
What PCIe generation and speed do HPE E3.S SSDs use?
HPE E3.S NVMe SSDs run on PCIe Gen5, typically over a x4 link, which roughly doubles the bandwidth of PCIe Gen4. A single Gen5 enterprise drive can reach throughput on the order of 14 GB/s with very low latency, making E3.S well suited to analytics, AI, and database workloads.
Can I install an E3.S drive in a 2.5-inch (U.2/U.3) bay?
No. E3.S is a different form factor with a different connector, so it requires a server built with EDSFF drive cages and the E3.S carrier. An E3.S drive will not fit a 2.5-inch U.2/U.3 bay, and a 2.5-inch drive will not fit an EDSFF cage.
Is EDSFF replacing 2.5-inch SSDs?
Gradually, in high-performance and high-density servers. EDSFF E3.S is the path forward for PCIe Gen5 NVMe density, but 2.5-inch U.3 remains widely used for its tri-mode flexibility (SAS, SATA, or NVMe in one bay), and 2.5-inch SAS/SATA drives remain common for capacity and compatibility. For now the two coexist, with the server's drive cages deciding which you use.
The bottom line
EDSFF E3.S is the form factor data center NVMe was heading toward: denser, cooler, and built for PCIe Gen5 and what comes after. On HPE ProLiant Gen11 and Gen12, it's the way to reach the highest flash density and bandwidth in a serviceable, front-loading design — provided the server is configured with EDSFF cages. Browse HPE EDSFF E3.S SSDs and other HPE DL380 Gen11 parts, or contact our team to match the right drive to your server.
