Hard Disk Drives: From Megabytes to the Terabyte Era and Beyond

Blog written by Rainer W. Kaese, senior manager, HDD business development, Toshiba Electronics Europe GmbH, published Dec 17, 2025

The journey of HDDs spans more than 60 years, transforming from bulky, low-capacity storage devices to the high-density, cost-effective solutions of today.

Originating in the 1950s, early HDDs were cabinet-sized and weighed nearly a ton, revolutionizing data processing by enabling more immediate access to information for selected computer and mainframe systems. The true ‘triumph’ of the hard disk, however, began in the 1980s with the advent of PCs.

Early Evolution and Standardization
In the early PC era, drives measuring 5.25 inches in form factor offered a mere few MB of data storage, such as the popular 20MB models. At the time, that storage capacity was sufficient given the lack of graphical user interfaces or storage-hungry digital media. Over the years, storage capacities quickly rose into the triple-digit Megabyte range, accompanied by the standardization of interfaces. The Molex connector became standard for power, while Parallel ATA (later PATA) and subsequently SATA became prevalent for data transfer, replacing the older ribbon cables.

The period also saw rapid consolidation within the industry. In 1985, there were 75 hard disk manufacturers, with over 200 companies attempting to produce drives over time. Today, only three remain active, as production became economically attractive only with large quantities.

Simultaneously, HDD form factors continuously shrank. The 3.5-inch HDD became widespread from the late 1980s, matching floppy disk drive bays and quickly becoming the standard for servers and storage systems, a position it largely maintains today. Smaller form factors, such as 2.5-inch drives for notebooks, emerged, though these are now primarily found in external USB drives due to the dominance of SSDs in laptops.

Even smaller drives, such as 1.8-inch HDDs (used in the first iPod in 2001) and 1-inch disks (for CompactFlash slots in digital cameras), briefly appeared. In the earlier 2000s, some smartphones even featured 0.85-inch models holding an impressive 4GB of data. However, flash memory ultimately outstripped HDDs in mobile devices, setting a lower limit for physical size reduction.

Capacity Breakthroughs: PMR, Helium, and Microwave Technology
The ‘flash boom’ necessitated that HDDs succeed by offering high capacities at favorable costs. A significant leap in capacity was achieved with PMR, a new recording method introduced in the mid-2000s. Unlike previous LMR, which aligned bits horizontally, PMR allowed a vertical arrangement, vastly increasing storage density.

Further capacity enhancements were achieved by filling HDDs with helium from the mid-2010s. This lightweight inert gas reduces friction and turbulence compared to air, enabling the use of thinner disks and creating space for additional platters within the enclosure. With nine disks and PMR, this innovation allowed for up to 16 Terabyte (TB) drives.

More recently, MAMR has emerged as a new recording method. This technology uses microwaves to control and focus the magnetic flux at the write head, reducing the energy needed to magnetize bits and enabling smaller recording heads and denser data writing.

Toshiba launched drives featuring a new form of MAMR, called flux-controlled MAMR (FC-MAMR), which boosted data storage capacity and improved power efficiency. The MG10 Series, released in 2022, features a 10-disk helium-sealed design that can store up to 22TB of data while maintaining the familiar 3.5-inch form factor.

The Future of Storage Technology
Building on FC-MAMR technology, Toshiba introduced the Mx11 family of helium-sealed Enterprise Capacity HDDs last year. This innovation demonstrates the potential for increased capacity within the same form factor, without requiring additional power consumption.

The MG11 Series utilizes CMR with FC-MAMR to provide capacities of up to 24TB. The MA11 Series, on the other hand, employs SMR to offer even higher capacities of up to 28TB. SMR is a technique for writing data to tracks that partially overlap, increasing the density and overall storage capacity per disk.

CMR is suited for Enterprise servers that handle different types of workloads. Whereas the industry is expected to pivot towards SMR technology for homogenous workloads that write in large chunks, with optimiZed cache buffering absorbing short bursts of random writing.

In the next development stage, microwave-assisted switching MAMR (MAS-MAMR), microwaves will activate the material of the magnetic disks to reduce energy input further and enable an even smaller write head. This requires new disk coatings and more precise microwave switching. MAS-MAMR, combined with further SMR development and thinner magnetic disks (now 0.55mm thick, allowing 11 disks in a 3.5-inch enclosure), is expected to increase HDD capacities to around 40TB in the next few years. Toshiba has already presented a prototype with 11 disks and a capacity of 31.24TB.

Looking further ahead, HAMR technology offers even greater potential. HAMR uses a laser diode to heat up the magnetic material to its Curie point, allowing bits to be aligned with very low magnetic energy. While MAMR primarily increases linear bit density, HAMR focuses on increasing track density.

HAMR will likely enable capacities of more than 40TB per drive, potentially reaching up to 50TB in the next few years, ensuring HDDs continue to bear the brunt of data storage in the information age. However, HAMR still needs further development to achieve the reliability and cost-efficiency of MAMR.

Driving Sustainability and Innovation
As large-scale decommissioning of early cloud infrastructure begins, a significant wave of HDD material is anticipated for recycling. HDDs are notably easier to recycle than other electronics, as they contain only two or three different metals, unlike the complex and potentially toxic compounds found in batteries. Cloud service providers are preparing for this influx, and HDD vendors are expected to become an integral part of the recycling process.

Toshiba recognizes the growing importance of closer collaboration with customers and other component manufacturers (such as servers, software, cables, and cards) to build a robust storage ecosystem. This commitment is underscored by the inauguration of the new HDD Innovation Lab in Düsseldorf, Germany, this year.

The lab expands Toshiba’s HDD evaluation capabilities to support customers and partners in optimizing HDD setups for various applications, including cloud storage, surveillance, and NAS systems. It provides a platform for proof-of-concept activities, benchmarking across various architectures, and sharing knowledge through white papers and lab reports. The lab also offers loan samples for self-evaluation and hosts live demonstrations at trade fairs.

This article is also available with illustrations in pdf format here.