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Silver rectangular 2.5 inch bare SATA laptop hard drive

Seagate

Seagate Momentus 5400.2 ST9120821AS 120GB 5400 RPM 8MB SATA 1.5Gb/s 2.5" laptop hard drive

SKU CH-ZKQ2-D27Y5 MPN ST9120821AS

A 120GB 2.5-inch laptop hard drive spinning at 5400 RPM with 8MB cache and a SATA 1.5Gb/s interface for low-power storage upgrades

  • Total capacity120 GB
  • Interface typeSATA 1.5Gb/s
  • Form factor2.5 in (6.35 cm)
  • Packaging typeBare Drive
  • Cache memory8 MB
  • Average seek time12.5 ms
  • 120 GB capacity stores documents and media
  • 5400 RPM spindle delivers responsive everyday performance
  • 8 MB cache speeds up frequent file access
  • SATA 1.5 Gb/s interface connects directly to laptop motherboards
  • 2 W seek power extends battery runtime

Capacity and interface

The Seagate Momentus 5400.2 ST9120821AS is a 120GB 2.5-inch laptop internal hard drive with a SATA 1.5Gb/s interface. It spins at 5400 RPM and includes an 8MB cache. The drive is supplied new as a bare unit without cables or brackets.

Who this suits

This drive suits owners of older notebooks or external enclosures that require a SATA 1.5Gb/s 2.5-inch drive for a direct replacement or a modest capacity upgrade. Low power draw of 2.2W seek and 0.28W standby helps preserve battery life. Buyers who need more than 120GB of storage or a faster 6Gb/s SATA link should consider other options.

Deciding specification

The SATA 1.5Gb/s interface is the single specification that decides compatibility. The host system must provide a matching SATA 150 port; drives with a 3Gb/s or 6Gb/s interface will not operate at their rated speed on this connection.

How it compares

Measured against everything we stock in 2.5-Inch Internal Laptop HDDs, at today’s prices. Recalculated every night.

Price $65.99
Typical for this category: the median of 645 items is $66.99.
Total capacity 120 GB
Lower than about 84% of the 419 comparable items (median 320 GB).
Price per TB $549.92 per TB
Pricier than about 79% of the 416 comparable items (median $233.48 per TB).

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Specifications

Product
Brand nameSeagate
Product lineMomentus 5400.2
Model nameST9120821AS
Total capacity120 GB
Performance
Average seek time12.5 ms
Mean write time14.5 ms
Mean latency5.6 ms
Rotational speed5,400 RPM
Storage
Cache memory8 MB
Ports & slots
Interface typeSATA 1.5Gb/s
Size & build
Form factor2.5 in (6.35 cm)
Shipping weight0.36 kg
Package size152 × 102 × 51 mm

Questions about this item

How can I confirm the drive is operating correctly after installation?

The drive should spin at 5400 RPM with an average seek time of 12.5 ms and average latency of 5.6 ms; the SATA 1.5Gb/s interface will report a 150 MB/s link speed in BIOS or OS tools.

What is included with the bare drive and what must I source separately?

Only the 2.5" ST9120821AS unit is supplied; you must provide a SATA data cable, a SATA power connection from the laptop or enclosure, and mounting screws or a caddy if required.

Which capacity from the Momentus 5400.2 line should I choose for a 120 GB requirement?

The ST9120821AS is the 120 GB model in the Momentus 5400.2 series, delivering 8 MB cache and 5400 RPM performance for that capacity.

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