Server drives are chosen by interface (SAS, SATA or NVMe), form factor (2.5-inch SFF, 3.5-inch LFF, U.2, M.2 or EDSFF), capacity, and either spindle speed for hard drives or endurance class for SSDs. The server's backplane and controller decide which interfaces and form factors fit.
Interfaces
| Interface | Typical speed | Used in | Notes |
|---|---|---|---|
| SATA | 6 Gb/s | HDD and SSD | Single port; lower cost; common for boot and capacity storage |
| SAS | 12 Gb/s (SAS-3), 22.5 Gb/s (24G SAS) | HDD and SSD | Dual port for redundant paths; needs a SAS controller or HBA |
| NVMe | PCIe Gen3, Gen4 or Gen5 lanes | SSD only | Connects over PCIe; much lower latency and higher throughput |
Key points:
- A SAS controller can usually run SATA drives as well. A SATA-only controller cannot run SAS drives.
- NVMe drives need an NVMe-capable backplane and PCIe connections from the motherboard or a tri-mode controller. A SAS/SATA bay does not take an NVMe drive unless the backplane supports it.
- Tri-mode controllers support SAS, SATA and NVMe in the same bays, on servers designed for them.
Form factors
- 3.5-inch LFF (large form factor): high-capacity hard drives. Lowest cost per terabyte.
- 2.5-inch SFF (small form factor): 10K and 15K hard drives, SAS and SATA SSDs. Most SFF server drives are 15 mm or 7 mm high.
- U.2: 2.5-inch NVMe SSDs with an SFF-8639 connector, usually 15 mm high. U.3 uses the same connector and works in tri-mode bays.
- M.2: small card-style SSDs, often used for boot drives. Common lengths are 2280 and 22110. M.2 drives can be SATA or NVMe, and the slot must support the right one.
- EDSFF (E1.S, E3.S): newer NVMe form factors designed for dense, well-cooled servers. They need servers built for them.
Browse hard drives and solid state drives.
Hard drive speed (RPM)
| RPM | Form factor | Use |
|---|---|---|
| 7,200 (7.2K) | Mostly LFF, some SFF | High capacity, backup, archive, file storage |
| 10,000 (10K) | SFF | Mixed workloads on older systems |
| 15,000 (15K) | SFF | Latency-sensitive workloads on older systems |
SSDs have largely replaced 10K and 15K drives in new systems. Those drives are still needed to maintain and expand existing arrays.
SSD endurance classes
SSD flash wears with writes. Manufacturers rate endurance as DWPD (drive writes per day: how many times the full capacity can be written each day over the warranty period) or TBW (total terabytes written).
| Class | Typical DWPD | Typical use |
|---|---|---|
| Read intensive (RI) | About 1 or less | Boot, web, read caching, content delivery |
| Mixed use (MU) | About 3 | Databases, virtualization, general workloads |
| Write intensive (WI) | About 10 or more | Logging, write caching, heavy transactional loads |
Exact ratings vary by model, so check the drive's specifications. To convert: TBW is roughly DWPD x capacity in TB x 365 x warranty years. For example, a 1.92 TB drive at 1 DWPD over 5 years is about 3,500 TBW.
For refurbished and used SSDs, the remaining endurance matters as much as the rating. Ask for SMART data such as percentage used or remaining life when it is important to you.
Sector format
- 512n: native 512-byte sectors. Mostly older and smaller drives.
- 512e: 4K physical sectors with 512-byte emulation. Works with most operating systems and controllers.
- 4Kn: native 4K sectors. Needs operating system and controller support.
Arrays usually require all drives to use the same format.
Security options
- SED (self-encrypting drive): encrypts data on the drive with a key managed by the controller or a key manager.
- FIPS 140 validated: SED models certified for use where FIPS is required.
Check that your controller and key management support the drive before you mix SED and non-SED drives.
Carriers and trays
Hot-swap server drives sit in a carrier (also called a tray or caddy) that fits the server's bays.
- Carriers differ by brand and often by server generation. An HPE carrier does not fit a Dell bay, and older carriers may not fit newer servers from the same brand.
- OEM drive option numbers often include the carrier. A bare OEM drive does not.
- Carriers can include status LEDs and, on some platforms, a chip that the server reads.
- Some systems accept non-OEM drives in an OEM carrier, but may show warnings or limit monitoring.
When you send a request, say whether you need the drive with its carrier, the carrier on its own, or the bare drive.
OEM drives vs drive maker models
Server brands sell drives made by Seagate, Western Digital, Toshiba, Samsung, Kioxia, Micron, Solidigm and others, with their own firmware and labels. The label usually shows both numbers. Arrays and RAID controllers on OEM servers often expect OEM firmware. See server part numbers explained.
Checklist for your request
- Server or storage system model.
- Drive part number already installed, if matching.
- Interface, form factor and capacity.
- RPM (HDD) or endurance class (SSD).
- Carrier needed or not.
- Condition, and whether you need health data or sanitization records.
Send your list as an RFQ, or use Source a Part for drives not in the storage drive catalog.