HDD Timeline

How to read it

Each point is one hard drive that its maker’s own release describes. It sits at the date of that release, the earliest source cited for the drive, which is the date of the announcement and not the date the drive reached shelves. Some releases announce samples, a drive in customer qualification or a ship date still to come, and the table says which. The chart shows 29 drives from 25 releases, running from 2004 to 2026, not every drive ever made.

The value is the largest capacity the release states for the drive or family. Where a release prints only a lower limit, such as 30TB and beyond, the marker is hollow and the table shows a plus sign. The scale is logarithmic, so each grid line is ten times the one below it, and the early drives in gigabytes sit on the same chart as the latest ones in terabytes.

The method chips filter by what each release says about how the drive writes its bits. Perpendicular says which way the bits point, and conventional (CMR) or shingled (SMR) says how the tracks are laid, so a release can name one, both or neither. A drive whose release names an energy assist is filed under that assist, then by track layout, then as perpendicular, and one whose release names no method at all is filed under not stated rather than guessed from what the maker shipped elsewhere.

The recording methods, first release in this data

The first release here to name each method, which is not always the first drive ever to use it. Seagate’s shingled first is a release about shipments with no one drive named, so it has no point on the chart.

Perpendicular (PMR)

Bits stand on end, at right angles to the platter, instead of lying flat along it as in the longitudinal recording before. First named here by Toshiba, 12/2004: MK8007GAH, 1.8-inch, 80GB (Toshiba 2004 release).

Conventional (CMR)

Tracks are written side by side with a gap between them, the layout shingled recording departs from. It says how tracks are laid, not which way the bits point. First named here by Seagate, 1/2016: Enterprise Capacity 3.5 HDD 10TB (Seagate 2016 release).

Shingled (SMR)

Each track is written partly over the last, like roof shingles, so more tracks fit but a rewrite has to redo its neighbors. First named here by Seagate, 9/2013: Shipped over one million shingled magnetic recording drives, and called itself the first maker to ship them (Seagate 2013 release).

Western Digital ePMR

Western Digital’s own name for its energy-assisted perpendicular recording: energy-assisted recording in 2019, ePMR from 2021. Microwave-assisted and heat-assisted recording are energy-assisted too, under their own names. First named here by Western Digital, 9/2019: Ultrastar DC HC550, 18TB (Western Digital 2019 release).

Microwave-assisted (MAMR)

Toshiba’s flux control microwave-assisted recording, FC-MAMR, which helps the write head switch the bits. First named here by Toshiba, 2/2021: MG09, 18TB (Toshiba 2021 release).

Heat-assisted (HAMR)

A laser heats a tiny spot of the platter as it is written, so a medium too stable to write cold can hold smaller bits. First named here by Seagate, 9/2020: 20TB HAMR drive (Seagate 2020 release).

What it will not tell you

A drive sits at the date of its release, not the date it shipped in volume. The chart covers drives with a saved maker release, not every drive ever made: a record set by a drive whose release is no longer online is missing, and so are drives whose makers have left the market. Capacity is the figure on the label, in decimal terabytes, not what an operating system reports.

It does not rank drives by speed, power or reliability, and it says nothing about how a shingled drive handles rewrites. For flash, see the NAND Die Timeline and the SSD Endurance Leaderboard.