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Silver 3.5 inch enterprise hard drive with SAS connectors

Seagate

Seagate Exos X18 ST12000NM004J 12TB 7200 RPM 256MB SAS 12Gb/s 3.5" internal hard drive

SKU CH-SH4R-QTWAH MPN ST12000NM004J

Enterprise 12TB SAS drive with 7200 RPM and 256MB cache for high-capacity storage

  • Total capacity12 TB
  • Interface typeSAS 12Gb/s
  • Form factor3.5 in (8.89 cm)
  • Flash memory typeHard Drive
  • Rotational speed7,200 RPM
  • Cache memory256 MB
  • 12TB capacity stores massive datasets in a single 3.5" bay
  • 7200 RPM spindle delivers sustained throughput for enterprise workloads
  • 256MB cache absorbs burst I/O to reduce latency
  • SAS 12Gb/s interface enables high-speed connectivity in scale-out systems
  • Helium-sealed design lowers power per terabyte for data-centre efficiency

Enterprise-capacity SAS drive

The Seagate Exos X18 ST12000NM004J is a 12TB 3.5-inch internal hard drive built for enterprise storage arrays. Its 7200 RPM spindle and 256MB cache serve workloads that demand sustained throughput across many petabytes. The helium-sealed design reduces weight and power per terabyte for large-scale deployments.

SAS 12Gb/s interface

The single specification that decides fit is the SAS 12Gb/s interface, which requires a compatible controller or backplane running at that link speed. A SATA-only host cannot use this drive, and a 6Gb/s SAS link will halve the available bandwidth. Verify the host bus adapter and cable plant before purchase.

Rack-density focus

This drive fits standard 3.5-inch hot-swap bays measuring 147.00mm long, 101.85mm wide and 26.10mm high, and it draws power from the backplane through the SAS connector. The helium seal and digital environmental sensors support continuous operation in dense racks, while Seagate Secure features simplify drive retirement. It is not for builders who need a SATA interface or desktop users without enterprise-class cooling and power infrastructure.

How it compares

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

Price $259.99
Pricier than about 78% of the 4,938 comparable items (median $107.99).
Total capacity 12 TB
Higher than about 90% of the 2,372 comparable items (median 2 TB).
Price per TB $21.67 per TB
Cheaper than about 91% of the 2,365 comparable items (median $62.21 per TB).

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Specifications

Product
Brand nameSeagate
Product lineExos X18
Model nameST12000NM004J
Total capacity12 TB
Recommended useFor Enterprise Storage
Performance
Rotational speed7,200 RPM
Mean latency4.16 ms
Storage
Flash memory typeHard Drive
Cache memory256 MB
Ports & slots
Interface typeSAS 12Gb/s
Size & build
Form factor3.5 in (8.89 cm)
Max height26.1 mm
Maximum width101.85 mm
Maximum length147 mm
Shipping weight0.64 kg
Package size196 × 152 × 76 mm

Questions about this item

How does the 12TB capacity translate into usable space once the drive is formatted in a server?

The drive presents 12TB of raw capacity; after formatting and RAID overhead the usable space will be slightly lower, but the full 12TB is available to the array controller.

What does the SAS 12Gb/s interface limit in real-world throughput?

The SAS 12Gb/s link caps the maximum burst transfer rate at 12Gb/s; sustained throughput is governed by the 7200 RPM platters and 256MB cache.

Will the 3.5 inch form factor with 26.10mm height fit in a standard hot-swap bay?

Yes, the drive measures 147.00mm long, 101.85mm wide and 26.10mm high, matching the standard 3.5 inch enterprise hot-swap tray dimensions.

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