Seagate
Seagate Exos X20 ST18000NM003D 18TB 3.5" SATA 7200 RPM 256MB internal hard drive
High-capacity 18 TB enterprise drive with 7200 RPM, 256 MB cache and helium-sealed design for low power per terabyte
- InterfaceSATA 6.0Gb/s
- Capacity18TB
- Recording TechnologyCMR
- RPM7200 RPM
- Cache256MB
- Average Latency4.16ms
- 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.
Highlights
- 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
Specifications
| Brand | Seagate |
|---|---|
| Series | Exos X20 |
| Model | ST18000NM003D |
| Interface | SATA 6.0Gb/s |
| Capacity | 18TB |
| Recording Technology | CMR |
| RPM | 7200 RPM |
| Cache | 256MB |
| Average Latency | 4.16ms |
| Features | Market-leading 20TB HDD offering the highest capacity available for more petabytes per rack* Highly reliable performance with enhanced caching, making it the logical choice for cloud data center and massive scale-out data center applications Hyperscale SATA model tuned for large data transfers and low latency PowerBalance feature optimizes Watts/TB Maximize total cost of ownership savings through lower power and weight with helium sealed-drive design Proven helium side-sealing weld technology for added handling robustness and leak protection Digital environmental sensors to monitor i |
| Usage | For Enterprise Storage |
| Form Factor | 3.5" |
| Height (maximum) | 26.10mm |
| Width (maximum) | 101.85mm |
| Length (maximum) | 147.00mm |
| Shipping weight | 0.91 kg |
| Package size | 196 × 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.
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