Exos X18 16TB vs Exos X20 20TB
The Exos X18 16TB and the Exos X20 20TB are both enterprise hard drives we supply tested from Hong Kong, and the figures below are the same ones published on each product page. They share 3 listed specification rows and separate on interface, sustained transfer, form factor, so the decision is less about "which is better" and more about which of those differences your platform or workload can actually use.
Nothing on this page is a price: used and refurbished hardware is repriced weekly, so both are quoted on request against confirmed stock with the date the quote holds until. If you are replacing a part, send the platform and we will confirm the population before you commit.
Side by side
Exos X18 16TB vs Exos X20 20TB specifications
| Specification | Exos X18 16TB | Exos X20 20TB |
|---|---|---|
| Recording | CMR, 7200 rpm, 256MB cache | CMR, 7200 rpm, 256MB cache |
| Interface | SATA 6Gb/s, 512e (4Kn and SAS variants exist) | SATA 6Gb/s, 512e (4Kn and SAS 12Gb/s variants exist) |
| Sustained Transfer | Up to 270 MB/s | Up to 285 MB/s |
| Form Factor | 3.5-inch, helium-sealed | 3.5-inch, 10-platter helium-sealed |
| Workload Rating | 550 TB/year | 550 TB/year |
| Reliability | 2.5M hours MTBF, 5-year class | 2.5M hours MTBF, 5-year class |
| Power / Security | PowerChoice idle management, Seagate Secure (ISE/SED options) | PowerBalance, Seagate Secure (ISE/SED options) |
| Model | Seagate Exos X18 16TB (ST16000NM000J / ST16000NM002H) | Seagate Exos X20 20TB (ST20000NM002H, SATA) |
Rows that differ are highlighted. Figures are the same ones published on each product page; where a figure is community-sourced rather than vendor-published it is stated on that page. Confirm every part against your build sheet when ordering.
Where they differ
- ·Interface — Exos X18 16TB: SATA 6Gb/s, 512e (4Kn and SAS variants exist); Exos X20 20TB: SATA 6Gb/s, 512e (4Kn and SAS 12Gb/s variants exist).
- ·Exos X20 20TB is the better figure for sustained transfer rate (Up to 270 MB/s vs Up to 285 MB/s).
- ·Form Factor — Exos X18 16TB: 3.5-inch, helium-sealed; Exos X20 20TB: 3.5-inch, 10-platter helium-sealed.
- ·Power / Security — Exos X18 16TB: PowerChoice idle management, Seagate Secure (ISE/SED options); Exos X20 20TB: PowerBalance, Seagate Secure (ISE/SED options).
What they share
Recording: CMR, 7200 rpm, 256MB cache; Workload Rating: 550 TB/year; Reliability: 2.5M hours MTBF, 5-year class.
Decision
Which one to buy
Hard drives are a density decision. Capacity per drive sets how many spindles — and therefore how much rack, power and cooling — a given usable capacity costs, and sustained transfer sets how long rebuilds and backups take. For bulk storage the highest capacity per drive usually wins on total cost of ownership; for arrays that are rebuilt often, the workload rating and transfer rate matter more than the headline capacity. Both models above are CMR enterprise parts — check the interface (SATA versus SAS) against your enclosure before ordering.
Choose the Exos X18 16TB if
- ·Interface: SATA 6Gb/s, 512e (4Kn and SAS variants exist)
- ·Form Factor: 3.5-inch, helium-sealed
- ·Power / Security: PowerChoice idle management, Seagate Secure (ISE/SED options)
Choose the Exos X20 20TB if
- ·Interface: SATA 6Gb/s, 512e (4Kn and SAS 12Gb/s variants exist)
- ·You need more sustained transfer rate — the Exos X20 20TB lists Up to 285 MB/s against Up to 270 MB/s on the Exos X18 16TB.
- ·Form Factor: 3.5-inch, 10-platter helium-sealed
Photos
What the two look like
Exos X18 16TB
Photo from the Exos X18 16TB page. Every unit's label is read against your order before dispatch.
Exos X20 20TB
Photo from the Exos X20 20TB page. Every unit's label is read against your order before dispatch.
Frequently asked questions
How much do the Exos X18 16TB and the Exos X20 20TB cost?
We do not publish prices for either: secondary-market hardware is repriced weekly. Send the quantity, the platform and the condition you want and we quote both against confirmed stock, with the date the figure holds until.
What is the main difference between the Exos X18 16TB and the Exos X20 20TB?
Interface (Exos X18 16TB: SATA 6Gb/s, 512e (4Kn and SAS variants exist); Exos X20 20TB: SATA 6Gb/s, 512e (4Kn and SAS 12Gb/s variants exist)); Sustained Transfer (Exos X18 16TB: Up to 270 MB/s; Exos X20 20TB: Up to 285 MB/s); Form Factor (Exos X18 16TB: 3.5-inch, helium-sealed; Exos X20 20TB: 3.5-inch, 10-platter helium-sealed).
Can I use the Exos X18 16TB and the Exos X20 20TB in the same system?
Yes, if the bays and interface match, and both are CMR parts. Mixed capacities are fine in most arrays, though your controller may require matched drives per RAID group.
Which one should I buy?
Buy the one whose strong points match the job: see the "Choose" section above. If you are replacing an existing part, send the platform or the old part number and we will confirm compatibility before you order.
What condition are they in, and do you ship worldwide?
Both are supplied tested with a 1-year written warranty. Condition is stated line by line before you order — new, decommissioned pull or OEM tray — and we ship worldwide from the Hong Kong warehouse with full export documentation, typically 3–7 days by air.
Get a quote for either — or both
Tell us the quantity, the platform and the condition you need. We confirm stock and put a firm figure in writing with the date it holds until.
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