We take cryptocurrency — so the coins you hold can buy real hardware.Pay in crypto, spend it on real hardware. Free insured shipping worldwide over $399. Plain, unbranded boxes, sent from Germany.Free insured shipping over $399. Your rate is locked for 30 minutes once checkout opens.Rate locked 30 minutes. Every item sealed, serial-checked and covered by a 24-month warranty.Sealed, 24-month warranty.

Saved items Sign in
Silver 3.5 inch hard drive with SATA connectors and label

Seagate

Seagate Exos X20 ST18000NM003D 18TB 3.5" SATA 7200 RPM 256MB internal hard drive

SKU CH-R44C-K4RRE MPN ST18000NM003D

High-capacity 18 TB enterprise drive with 7200 RPM, 256 MB cache and helium-sealed design for low power per terabyte

  • Total capacity18 TB
  • Interface typeSATA 6.0Gb/s
  • Form factor3.5 in (8.89 cm)
  • Recording methodCMR
  • Rotational speed7,200 RPM
  • Cache memory256 MB
  • Massive 18 TB capacity stores more data per drive
  • CMR recording technology delivers consistent write performance
  • 7200 RPM spindle speed enables fast sequential access
  • 256 MB cache buffers bursts for smoother throughput
  • Helium sealed design reduces power draw per terabyte

18 TB enterprise SATA drive

The Seagate Exos X20 ST18000NM003D is an 18 TB 3.5 inch hard drive built for enterprise storage workloads. It uses conventional magnetic recording and spins at 7200 RPM with a 256 MB cache to sustain high-throughput operations in data-centre racks.

SATA 6.0 Gb/s throughput ceiling

The SATA 6.0 Gb/s interface caps sustained transfer rates at the bus limit, so sequential performance cannot exceed that ceiling regardless of the drive’s internal speed. Average latency sits at 4.16 ms, which is typical for 7200 RPM mechanics under random access patterns.

Helium-sealed 20 TB platform at 18 TB

This unit shares the helium-sealed platform that scales to 20 TB, delivering lower power per terabyte and reduced weight compared with air-filled designs. Buyers who need the absolute maximum capacity on the same platform should note that a higher-capacity variant exists.

How it compares

Measured against everything we stock in 3.5-Inch Internal Desktop HDDs, at today’s prices. Recalculated every night.

Price $333.99
Pricier than about 85% of the 4,938 comparable items (median $107.99).
Total capacity 18 TB
Higher than about 93% of the 2,372 comparable items (median 2 TB).
Price per TB $18.56 per TB
Cheaper than about 93% of the 2,365 comparable items (median $62.21 per TB).

New to this? Paying with USDT: TRC-20 or ERC-20 — what to check, what it costs to pay, and what is never asked for.

Specifications

Product
Brand nameSeagate
Product lineExos X20
Model nameST18000NM003D
Total capacity18 TB
Recommended useFor Enterprise Storage
Performance
Rotational speed7,200 RPM
Mean latency4.16 ms
Storage
Recording methodCMR
Cache memory256 MB
Ports & slots
Interface typeSATA 6.0Gb/s
Size & build
Form factor3.5 in (8.89 cm)
Max height26.1 mm
Maximum width101.85 mm
Maximum length147 mm
Shipping weight0.91 kg
Package size196 × 152 × 76 mm

Questions about this item

Should I pick the 18TB Exos X20 or a smaller capacity in the same series?

The 18TB model delivers the highest capacity in the Exos X20 line with CMR recording and 256MB cache, ideal when you need maximum petabytes per rack in a single 3.5" bay.

What does the 7200 RPM rating mean for real-world throughput in a server?

At 7200 RPM with 4.16ms average latency and a 256MB cache, the drive sustains high sequential transfer rates suited for hyperscale workloads and large data transfers.

How does the SATA 6.0Gb/s interface limit performance compared to the drive's internal speed?

The SATA 6.0Gb/s link caps burst transfers at 6.0Gb/s, while sustained reads and writes are governed by the 7200 RPM CMR mechanism and 256MB cache.

More in 3.5-Inch Internal Desktop HDDs

Similar items