Hard disk drives (HDDs) have been around since the 1950s, when IBM produced the first commercial model. Since then, HDDs have come to dominate the storage market for personal computers, servers and data centers. Though other storage technologies like magnetic tape or floppy disks were popular in the past, HDDs now make up over 90% of storage shipments (https://www.linkedin.com/pulse/hard-disk-drives-market-size-2023-growth-opportunities-jtvbf).
HDDs remain popular due to their low cost per gigabyte and high data capacity. However, some limitations like slower speeds, higher power consumption, noise and fragility have led to the rise of solid state drives (SSDs). SSDs offer greater durability, silent operation and faster speeds, though at a higher price point. This has fueled speculation that SSDs will eventually displace HDDs in most applications. While HDD sales still dwarf SSD sales, the future looks less certain for these traditional drives.
Advantages of HDDs
Hard disk drives (HDDs) have been the dominant storage technology for decades due to several key advantages. First, HDDs offer a very low cost per terabyte of storage compared to solid state drives. This allows consumers to purchase drives with huge capacities at affordable prices. For example, 10TB HDDs now retail for around $200, while 10TB SSDs cost over $2,000 (https://blog.internxt.com/cloud-storage-vs-hard-disk/). The mature, proven technology behind HDDs enables the production of high capacity drives at continually lower costs.
In addition, HDDs can offer massive storage capacities of 10TB or more in a standard 3.5″ drive format. The highest capacity SSD currently available is 100TB, but that comes in a special proprietary form factor and costs tens of thousands of dollars. HDDs will continue to have a significant advantage in terms of maximum drive capacities for the foreseeable future (https://robots.net/tech/what-is-a-hard-disk-drive-hdd/). The huge capacities make them well-suited for applications like network attached storage (NAS) and backup drives.
Disadvantages of HDDs
HDDs have some key disadvantages compared to SSDs. First, HDDs are slower due to the mechanical nature of their spinning platters and moving read/write heads. Typical HDDs have speeds around 100-200 MB/s, while SSDs are 3-4x faster at 500 MB/s or more for SATA SSDs and over 3,000 MB/s for NVMe SSDs (Phiston, 2023). The mechanical parts of HDDs also contribute to higher latency of around 5-10 ms versus 0.1 ms for SSDs.
In addition, HDDs are more prone to failure over time due to their moving parts. Annualized failure rates for consumer-grade HDDs are around 2-3%, while SSDs have failure rates under 1% (Backblaze, 2021). HDDs are also more susceptible to damage from drops, vibration, magnets, and extreme temperatures compared to SSDs.
Overall, the disadvantages of lower speed, higher latency, and less physical durability make HDDs less ideal for applications requiring fast access, sustained performance, or resilience such as in servers, high-end desktops, and portable devices where SSDs are now favored (CHTips, 2021). However, HDD capacities and cost efficiency still give them advantages for bulk storage and backups.
Growth of SSDs
In recent years, solid state drives (SSDs) have been rapidly gaining market share over traditional hard disk drives (HDDs). There are several key advantages driving the growth of SSD adoption:
Faster speeds – SSDs have much faster read/write speeds compared to HDDs. For example, a SATA SSD may have speeds of 500 MB/s compared to only 100 MB/s for a HDD. This makes a huge difference in boot times and application launch times.
Lower latency – Because SSDs don’t have moving parts, they have much lower access times typically less than 0.1 ms compared to 3-15 ms for HDDs. This reduced latency provides a snappier overall system performance.
More durable – With no moving parts, SSDs are less susceptible to damage or failure from shock, vibration, or magnetism. SSDs have a longer lifespan on average and lower failure rates than HDDs.
With these significant performance advantages, SSD costs have dropped dramatically in recent years. As a result, SSDs are now prevalent in consumer laptops, high-end PCs, and data centers. The SSD market is projected to keep growing at double digit rates for the foreseeable future.
Uses Favoring HDDs
HDDs still have a number of advantages for specific use cases compared to SSDs which have helped them maintain a role going forward. Some key areas where HDDs are favored include:
Low-Cost Bulk Storage
HDDs continue to offer substantially lower cost per gigabyte of storage compared to SSDs. For users or organizations needing large amounts of storage, such as in the multi-terabyte range, HDDs remain very cost effective. Bulk storage applications where absolute performance is not critical can utilize high capacity HDDs for an efficient way to store large archives of data. (Top 5 Uses for External Hard Drives)
Archival Storage
The lower cost of HDDs also makes them well-suited for long-term archival storage. If data will rarely be accessed after being stored, the slower speeds of HDDs are less of a factor. The lower cost per gigabyte makes mass storage of archival data much more affordable. (3 Reasons You Should Still Buy a Hard Drive)
Enterprise Server Storage
HDDs are still commonly used in enterprise storage servers where large amounts of data need to be stored at the lowest cost per gigabyte. The total storage capacity potential with HDDs remains far greater than SSDs currently. Enterprise-optimized HDDs are built for 24/7 operation and high reliability when used in storage arrays and servers. (3 Reasons You Should Still Buy a Hard Drive)
Uses favoring SSDs
SSDs tend to be preferred over HDDs for certain use cases that benefit from the advantages they provide:
Performance-critical applications
Because SSDs have much faster read/write speeds compared to HDDs, they excel in applications where performance is critical. For example, SSDs are ideal for gaming systems where fast load times are desired, or data analytics tasks that involve processing large datasets quickly.1
Mobile devices
Since SSDs are lighter, more compact, and more shock-resistant than HDDs, they are the default storage technology for mobile devices like laptops, tablets, and smartphones. The benefits of durability, low power consumption, and fast performance make SSDs well-suited for mobile computing.2
Boot drives
SSDs can dramatically decrease boot times for operating systems because of their fast data access. For this reason, many people use SSDs as their primary boot drive, keeping the OS and key applications on the SSD while using HDDs for bulk storage of files and data.3
Hybrid drives
Hybrid hard disk drives (HDDs) combine the high storage capacity of traditional HDDs with the performance boost of solid-state drives (SSDs). As a middle ground between HDDs and SSDs, hybrid drives offer more speed than HDDs but less than SSDs, while providing more storage capacity than SSDs but less than HDDs (Best Buy).
Hybrid drives integrate a small SSD, usually 8-32GB, as a cache for an HDD, which is typically 500GB to 2TB. Frequently accessed data like the operating system and programs are stored on the SSD for faster loading times, while less accessed data like documents are stored on the larger HDD. This hybrid design takes advantage of the strengths of each storage technology (Robots.net).
Hybrid hard disk drives serve as a compromise, aiming to deliver both enhanced performance and large capacities at a reasonable cost. For many consumers looking to upgrade their storage without breaking the bank, hybrid drives present an appealing middle ground option (Webopedia).
Long-term projections
While HDD sales are expected to decline over the next few years, they are not projected to disappear entirely. SSDs are expected to overtake HDDs in unit sales for consumer PCs and laptops, thanks to their faster speeds and smaller form factors. However, HDDs still have advantages in high capacity, bulk storage applications.
HDD shipments are projected to decline at around 15% per year, as SSDs take over more of the consumer market. However, total HDD storage capacity shipments are only expected to decline at around 3% per year, indicating HDDs will still be used for high capacity storage needs.
Data centers, NAS devices, surveillance systems, and other applications requiring large storage capacities will continue to rely on HDDs. Their lower costs-per-gigabyte make them better suited for bulk storage, especially at high capacities of 1TB or more.
So while SSDs will likely become the dominant storage technology in PCs and laptops, HDDs are not going away soon. Their unique advantages for high capacity storage ensure they will still have a place in the storage market.
New HDD innovations
HDD manufacturers continue to innovate to increase capacity and improve performance. Some key innovations include:
Shingled Magnetic Recording (SMR) overlaps tracks to increase areal density. SMR drives are well-suited for sequential write workloads like backups and archives (Computer History Museum, 2014).
Heat-assisted magnetic recording (HAMR) uses laser heating to temporarily change the magnetic properties of high storage density media, enabling further increases in areal density. HAMR is expected to enable hard drives over 40TB (Coughlin, 2023).
Microwave-assisted magnetic recording (MAMR) is another technology that aims to push HDD areal density higher by using microwave radiation to make the media easier to magnetize (TechRadar, 2023).
Helium-filled HDDs reduce turbulence and friction, enabling more platters to be packed into a drive. This increases capacity and reduces power consumption (Coughlin, 2023).
Conclusion
While solid state drives are increasingly being used in many applications that require faster performance, hard disk drives remain essential storage devices for numerous use cases. HDDs continue to offer advantages like massive storage capacities and affordability that make them preferable for data archiving, NAS devices, backups, surveillance systems, and other roles where sheer volume is more important than speed.
Though HDDs are clearly being phased out in client devices and enterprise applications where speed is critical, they retain relevance due to their unique strengths. Continued innovations like SMR, HAMR, MAMR, and helium-filled drives allow HDDs to increase their capabilities and remain competitive with SSDs for capacity-driven workloads. Rather than disappearing entirely, HDDs look to occupy an important niche in the storage ecosystem for the foreseeable future.