A 16TB to 24TB enterprise hard drive is a 3.5in, 7,200 rpm drive for servers and storage arrays, sold by Seagate (Exos), Western Digital (Ultrastar) and Toshiba (MG series), and rebadged by server brands such as HPE, Dell and Lenovo. Choose it by interface (SATA 6Gb/s or SAS 12Gb/s), sector format (512e or 4Kn), encryption (standard, SED or ISE) and whether your server needs an OEM part number and carrier.
Who these drives are for
High-capacity hard drives store the most data per bay at the lowest cost per terabyte. Typical uses:
- Backup repositories and archive storage.
- File servers and object storage.
- Video surveillance and media storage.
- Capacity tiers in software-defined storage, with SSDs for cache or hot data.
They are not the right choice for random-I/O workloads such as busy databases or virtual machine boot storms. Use SSDs for those. Our guide to SAS, SATA and NVMe drives covers the trade-offs.
Drive families in our catalog
Every drive below is a 3.5in LFF, 7,200 rpm hard drive. Specifications come from manufacturer data sheets held in our catalog.
| Family | Capacities | SATA example | SAS example |
|---|---|---|---|
| Seagate Exos X18 | 16TB, 18TB | ST18000NM000J | ST18000NM004J |
| Seagate Exos X20 | 18TB, 20TB | ST20000NM007D | ST20000NM002D |
| Seagate Exos X24 | 24TB | ST24000NM002H | - |
| WD Ultrastar DC HC550 | 16TB, 18TB | WUH721818ALE6L4 | WUH721818AL5204 |
| WD Ultrastar DC HC560 | 20TB | WUH722020ALE6L4 | WUH722020BL5204 |
| WD Ultrastar DC HC570 | 22TB | WUH722222ALE6L4 | WUH722222AL5204 |
| WD Ultrastar DC HC580 | 22TB, 24TB | WUH722424ALE6L4 | WUH722424AL5204 |
| Toshiba MG08 | 16TB | MG08ACA16TE | MG08SCA16TE |
| Toshiba MG09 | 16TB, 18TB | MG09ACA18TE | MG09SCA18TE |
The Seagate Exos X24 24TB lists a 512 MB cache. Browse every capacity in hard drives, or by brand: Seagate, Western Digital and Toshiba.
SATA or SAS?
| SATA | SAS | |
|---|---|---|
| Interface speed | 6 Gb/s | 12 Gb/s |
| Ports | Single | Dual port, for redundant paths |
| Works on | SATA and SAS controllers | SAS controllers only |
| Typical use | Single-server storage, backup targets, cost-focused builds | Storage arrays, JBODs with dual controllers, multipath setups |
A single hard drive cannot use the full bandwidth of either link, so the choice is mostly about the controller and redundancy. Choose SAS when your enclosure or array uses dual paths, such as a dual-controller storage array. Choose SATA when cost matters and the drive connects to one controller. A SATA drive works on a SAS controller; a SAS drive does not work on a SATA-only controller.
512e or 4Kn?
Modern high-capacity drives use 4K physical sectors. The difference is what the drive reports to the system.
- 512e (512 emulation) reports 512-byte logical sectors. It works with almost every operating system, hypervisor and RAID controller. Most drives in this guide are 512e.
- 4Kn (4K native) reports 4K logical sectors. It avoids emulation, but needs operating system, controller and software support.
Some models come in both formats. For example, Toshiba lists the MG09ACA18TE as 512e and the MG09ACA18TA as 4Kn. Do not mix formats in one RAID array. If you are expanding an array, match the format of the drives already installed.
Standard, SED or ISE?
- Standard drives have no hardware encryption.
- ISE (Instant Secure Erase) drives can be cryptographically erased in seconds, which helps with redeployment and disposal.
- SED (self-encrypting drive) models encrypt all data on the drive and need a key manager, usually in the RAID controller or storage array, to lock and unlock them. Some SED models are FIPS validated, which certain regulated buyers require.
SED variants have their own part numbers. For example, the Seagate Exos X20 20TB SAS is ST20000NM002D and its SED version is ST20000NM003D. Only buy SED drives if your controller or array is set up to manage them.
OEM drives for servers and arrays
Server brands sell the same drives under their own part numbers, often with a carrier and firmware for their platforms.
| Brand | Example | What it is |
|---|---|---|
| HPE | P53553-B21 | 20TB SAS 12G LFF, low-profile carrier, 512e |
| HPE | P23449-B21 | 16TB SATA 6G LFF, low-profile carrier, 512e |
| Lenovo | 4XB7A93784 | 20TB SAS 12G LFF hot-swap, listed for SR630 V2, SR650 V2, SR650 V3 and others |
| Dell | R3G03 | 20TB SAS LFF, listed in the Dell support matrix for PowerVault ME5 |
| Dell | GPP63 | 24TB SAS LFF, listed for PowerVault ME5 |
For servers and arrays under OEM support, use the OEM part number. For out-of-warranty systems, a drive-maker model with the right carrier can work if the controller accepts it. See server part numbers explained.
Buying checklist
- Server or array model, and the controller the drives connect to.
- Capacity and quantity, including hot spares.
- Interface: SATA or SAS.
- Sector format: 512e or 4Kn, matching existing drives.
- Encryption: standard, ISE or SED (and FIPS if required).
- OEM part number and carrier, if the system needs them.
- Condition: new, refurbished or used. For hard drives, ask about power-on hours and SMART health. See new vs refurbished vs used.
Add your drives to an RFQ, or paste a list of part numbers with quantities. For a model we do not list, use Source a Part. We reply within 1 business day.
FAQ
Is SAS faster than SATA for a 20TB hard drive?
The SAS link is faster (12 Gb/s vs 6 Gb/s), but one hard drive cannot fill either link. SAS adds dual-port support for redundant paths. Choose by controller and enclosure, not by link speed.
Can I mix 512e and 4Kn drives?
Not in the same RAID array or storage pool. Different arrays in the same server can use different formats if the controller and operating system support both.
What is the difference between Exos X18 and Exos X20?
They are successive Seagate families. In our catalog, Exos X18 covers 16TB and 18TB, and Exos X20 covers 18TB and 20TB, each in SATA and SAS versions.
Do I need SED drives?
Only if your security policy requires encryption at rest and your controller or array can manage the keys. Otherwise, standard or ISE drives are simpler to deploy.