The Origins of Hard Disk Drive
It has been almost seven decades since IBM created the world’s first hard disk drive—the IBM 350 disk storage unit. Used as the primary storage in the IBM 305 RAMAC computer, it was the first device that could access information randomly. Labeled as “miracle memory,” the IBM 350 made information retrieval exponentially faster—from hours or days to mere seconds. However, its development wasn’t without hiccups.
The groundwork was laid in 1952 by a group of IBM engineers—led by the father of HDD, Reynold B. Johnson—in a remote swath of land now known as Silicon Valley. However, just a year into its development, the project was cancelled by IBM’s board of directors, possibly because it would have impacted the sales of the highly profitable Hollerith punched cards. However, Rey Johnson decided to not heed the order and continued working on the project.
After dealing with technical and designing hurdles for four years, Reynold’s team at IBM’s San Jose Laboratory finally presented the RAMAC 305—a cabinet-sized machine that weighed more than a ton. Its memory unit, the IBM 350 hard drive, comprised 50 24-inch discs (platters), each spinning at 1200 rpm, with a total storage of 3.75 MB (Model 1). However, compared to existing computing systems, it was revolutionary. It could store the equivalent of roughly 64,000 punched cards and access the data instantaneously.
Although ground-breaking for their time, early hard drives were bulky, expensive, and fragile and offered limited storage capacity. For example, 5.25-inch HDDs were in circulation even at the turn of the century. Quantum released the Bigfoot TX series in late 1990s. It is more than ten times as bulky and with a thousand times less storage capacity than the 2.5-inch HDDs currently in circulation. See the image below for comparison.
Today, hard drives have evolved to fit in the palm of one’s hand and offer terabytes of storage. Consequently, global data creation has seen exponential growth in the last two decades.
In this article, we will explore in detail the remarkable evolution of hard disk drives (HDDs) and how they continue to shape our digital world.
The Evolution of Hard Drives
To a computer user, the evolution in hard drive technology becomes evident when:
- the storage capacity goes up;
- the cost per GB of storage goes down;
- the size and weight of hard drives reduce; and
- the performance characteristics of hard drives improve.
The first three of these categories will be discussed in this article.
Evolution of HDDs in Terms of Storage Capacity
Ever since the inception of hard drives, their storage capacity has followed Moore’s law, that is, it has historically doubled every 2–3 years (with some variability). From less than 5 MB in 1957 to 32 TB in 2025, HDD capacities have grown at an enormous compound annual growth rate.
Note: The doubling rate has slowed somewhat in recent years compared to the last century. This is because there are physical limitations on the superparamagnetic limits of conventional media like HDDs.
The following table charts the growth of HDD capacity from 1957 till today.
| Year | HDD Name / Model | Capacity |
|---|---|---|
| 1957 | IBM 350 (RAMAC) | 3.75 MB |
| 1964 | IBM 2311 | ~7.25 MB |
| 1970 | IBM 3330 “Merlin” | ~100 MB |
| 1973 | IBM 3340 “Winchester” | 35 MB or 70 MB |
| 1979 | IBM 3370 | ~571 MB |
| 1980 | IBM 3380 | ~2.52 GB (2 × 1.26 GB) |
| 1980 | Seagate ST-506 (5.25″) | 5 MB |
| 1983 | Rodime RO351/RO352 (3.5″) | 10 MB |
| 1988 | PrairieTek 220 (2.5″) | 20 MB |
| 1991 | IBM 0663 “Corsair” (3.5″) | ~1 GB |
| 1994–1997 | Various Desktop HDDs | Up to ~16 GB |
| 1999 | IBM Microdrive (1″ form factor) | 170 MB & 340 MB |
| 2004–2006 | Mainstream Desktops | ~200–300 GB |
| 2007 | Hitachi Deskstar 7K1000 | 1 TB |
| 2009 | Western Digital 2.5″ HDD | 1 TB |
| 2013 | Helium-Filled HDDs (introduced by HGST) | Up to 6 TB |
| Late 2010s | Various Enterprise HDDs | 10–18 TB |
| 2021 | Seagate HAMR Drives | 20 TB |
| 2024 | Seagate Exos M | 32 TB |
| 2025 | Seagate Exos M (upgraded) | 36 TB |
Note: As per Seagate CEO Dave Mosley’s announcement in January 2025, a 60 TB hard disk will enter the market before 2030. However, this HDD, like the 32 TB and 36 TB variants, will most likely not be available on retail because of high enterprise demand. As of 2025, the largest internal HDD on sale for individual users is the Western Digital Gold Enterprise HDD, with a capacity of 26TB.
As capacity soared and R&D costs rose, many HDD manufacturers exited or merged. Only three main manufacturers remain (Seagate, Western Digital, Toshiba). This smaller set of players invests heavily in complex technologies (e.g., helium, HAMR) to push capacity further and pull the costs down.
Evolution of HDDs in Terms of Cost per GB
1956: $109,000,000/GB or ₹9,37,40,00,000/GB (value in 2025; inflation adjusted)
1980: $122,650/GB or ₹1,06,17,500/GB (value in 2025; inflation adjusted)
2025: $0.031/GB or ₹2.7/GB
In 1980, IBM introduced the 3380 Direct Access Storage Device, the world's first gigabyte-capacity hard drive. It comprised two 1.26 GB hard disk assemblies and had a data transfer rate of 3 MB/sec.
Initially, six models of the IBM 3380 were released, with prices ranging from $81,000 to $142,200. Lease charges ranged from $1,800 to $3,713 a month. This translates to a cost of about $32,143 per GB (₹27,82,500/GB) for the cheapest model at that time (equivalent to $122,650 or ₹1,06,17,500 in 2025).
Currently, a 4-terabyte (TB) external hard disk drive is available in India for approximately ₹11,000. This equates to a cost of about ₹2.7 or $0.031 per GB.
This significant reduction in cost per GB, from nearly ₹10 million to ₹2.7, highlights the remarkable advancements in hard disk drive technology and manufacturing efficiency over the past 70 years. The table below shows how significantly the prices of hard disk drives have gone down and the capacity has increased during this period.
| S/N | Year | Company | Model | Form Factor | Capacity | Cost (US$) | Price/GB (US$)* |
|---|---|---|---|---|---|---|---|
| 1 | 1956 | IBM | 350-1 | 24″ | 3.75 MB | 34,500 | 9,200,000 |
| 2 | 1959 | IBM | 350-3 | 24″ | 7.5 MB | 57,000 | 7,600,000 |
| 3 | 1960 | IBM | 1405-1 | 24″ | 10 MB | 36,000 | 36,00,000 |
| 4 | 1964 | IBM | 2311-1 | 14" | 7.25 MB | 25,510 | 3,520,000 |
| 5 | 1966 | IBM | 2314 | 14″ | 29.2 MB | 30,555 | 1,048,000 |
| 6 | 1970 | IBM | 3330-1 “Merlin” | 14″ | 100 MB | 25,970 | 259,700 |
| 7 | 1974 | IBM | 3330-II | 14″ | 200 MB | 37,000 | 185,000 |
| 8 | 1985 | Seagate | ST-225 | 5.25″ HH | 20MB | 695 | 34,750 |
| 9 | 1988 | Seagate | ST-238 | 5.25” HH | 30 MB | 299 | 10,000 |
| 10 | 1990 | Seagate | ST227R-1 (RLL) | 3.5″ | 65 MB | 339 | 522,000 |
| 11 | 1995 | Conner | CP1275 (IDE) | 3.5″ | 1.3 GB | 278 | 214,000 |
| 12 | 2000 | Seagate | Elite 47GB (SCSI) | 5.25″ | 47 GB | 695 | 14,800 |
| 13 | 2005 | Seagate | 400GB 7200.8 (ATA-150) | 3.5″ | 400 GB | 249 | 0.623 |
| 14 | 2010 | WD | 2TB WD20EARS (SATA-2) | 3.5″ | 2 TB | 99.99 | 0.05 |
| 15 | 2015 | Seagate | 3TB ST3000DM001 (SATA-3) | 3.5″ | 3 TB | 89.99 | 0.03 |
| 16 | 2020 | Seagate | 8TB ST8000DM004 (SATA-3) | 3.5″ | 8 TB | 129.99 | 0.0162 |
| 17 | 2021 | Seagate | 8TB ST8000DM004 (SATA-3) | 3.5″ | 8 TB | 154.99 | 0.0194 |
| 18 | 2022 | WD | 6TB WD60EZAZ (SATA-3) | 3.5″ | 6 TB | 89.99 | 0.015 |
| 19 | 2024 | Seagate | 8TB NE-ST8000DM004 | 3.5″ | 8 TB | 111.98 | 0.014 |
| 20 | 2025 | Seagate | Exos M | 3.5″ | 32 TB | 480 | 0.015 |
*The prices are not inflation-adjusted.
Abbreviations:
- HH: Half-Height – Refers to the vertical space the HDD occupies in a rack or chassis.
- RLL: Run-Length Limited – A type of encoding used for magnetic storage data.
- SCSI: Small Computer System Interface – A set of standards for connecting and transferring data between computers and peripheral devices.
- ATA/IDE/PATA: Advanced Technology Attachment – An interface standard for connecting storage devices; also known as Integrated Drive Electronics and Parallel ATA; developed by Western Digital and Compaq in 1986.
- SATA: Serial ATA – A computer bus interface for connecting hard disk drives, SSDs, and optical drives to the motherboard; first released in January 2003.
Evolution of HDDs in Terms of Form Factor
In the 1950s, a hard drive of a few MBs was as big as two large refrigerators. Here is a photograph of one such hard drive (IBM 350) being transported via an airplane.
Imagine how different this is from the HDD form factors you're more familiar with: the 3.5-inch HDD for your desktop and the 2.5-inch HDD for your laptops.
Note: The term "form factor" in electronic devices refers to the physical dimensions and design specifications of a device. For hard disk drives (HDDs), form factor denotes the diameter of the platter inside the drive. This measurement, in most cases, offers a rough indication of the overall size of the HDD.
Today, the most common HDD form factors are 3.5 inch, used in desktops and servers, and 2.5 inch, used in laptops and portable drives. Historically, however, HDDs have undergone significant changes in form factor. Here's a chronological overview of this evolution:
- 1950s–70s: In the early decades, HDDs used to be cabinet-sized devices that were used in mainframe systems. HDDs in the 1950s and early 60s had a form factor of 24 inch, comprised up to 50 platters, and could weigh almost 1 ton.
In 1962, IBM developed the IBM 1311, which had a form factor of 14 inch and was the size of a washing machine. This form factor remained the industry standard for almost two decades. - 1980s: The M2351A Eagle, introduced by Fujitsu in mid 1980s, had a form factor of 10.5 inch and weighed around 65 kg. For a brief period, manufacturers experimented with 8-inch HDDs. However, the popularity of the Personal Computer (PC) accelerated the innovation in HDDs, and 5.25-inch HDDs with storage capacity of about 20 MB became the norm.
- Late 1980s: This is when 3.5-inch drives became widely available. This form factor has remained the standard for PCs and servers ever since.
- 1990s: As laptops became popular, 2.5-inch HDDs came into circulation. Even today, most laptop HDDs and external USB drives continue to be 2.5 inches.
- Early 2000s: 1.8-inch HDDs could be seen in the market, used in laptops and MP3 players. Also around this time, 1-inch drives were being used in MP3 players and digital cameras. Additionally, 0.85-inch drives with up to 4 GB of storage were used in some early smartphones. However, these became obsolete as flash memory started becoming more affordable around this time.
- Mid-2010s: 3.5-inch drives with a capacity of up to 16 TB were possible because of something known as the helium-sealed design. This technology allowed manufacturers to use thinner discs, which meant additional platters could be used in the hard drive.
- Early 2020s: The latest technology in HDD is Microwave Assisted Magnetic Recording (MAMR). One of the examples of this is Toshiba's MG10 series, which continues to use the 3.5-inch form factor but extends the capacity to up to 20 TB. It is expected that future innovations similar to MAMR can pave the way for the 3.5-inch form factor to have up to 100 TB capacity.
Here is a table showing how form factors have evolved over the years, along with a corresponding increase in capacity.
| Form Factor | Time Period | Primary Use | Typical Capacity | Notable Features |
|---|---|---|---|---|
| 24" & 14" | 1950s | Mainframe systems | A few MB | Large and heavy; revolutionized data processing; weighed nearly a ton. |
| 5.25" | 1980s | Early PCs | 10-40 MB | First widely used in PCs; sufficient for text-based applications. |
| 3.5" | Late 1980s – Present | PCs, servers, storage systems | Up to 36 TB | Became the standard for desktops; later optimized with He-sealed designs, PMR, SMR, and MAMR for increased capacity. |
| 2.5" | 1990s – Present | Notebooks, external USB drives | 40 GB–8 TB | Compact size for portable devices; now mostly replaced by SSDs in laptops. |
| 1.8" | Early 2000s | MP3 players, compact notebooks | 10–320 GB | Compact and lightweight; used in portable devices before flash memory became affordable. |
| 1" | Early 2000s | MP3 players, digital cameras | 5–10 GB | Could fit into CF card slots; replaced by flash memory. |
| 0.85" | Early 2000s | Smartphones | 2–4 GB | Smallest HDD; short-lived as flash memory took over. |
Other Breakthroughs in HDD Performance
Capacity, cost, and size are the three most evident characteristics that signify the rapid evolution of hard drive technology. Consequently, these are also the features on which most people judge how cutting-edge a newly released hard drive is. However, there are some more characteristics that are just as noteworthy.
The advancements in cache, seek time, spindle speed, areal density, etc. have a direct bearing on the capacity and performance of an HDD. In the next article, we will talk about these performance characteristics and how major technological breakthroughs have made hard disk drives faster, more durable, and less prone to errors.
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