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Mechanical hard drives have some advantages like large storage capacities and low cost per gigabyte. However, they also have significant downsides like slower speeds, higher failure rates, larger physical size, noise, and heat output. For most consumer use cases, SSDs are now a better option than mechanical drives. However, mechanical drives still have a place for large, infrequently accessed storage.
Mechanical hard disk drives have been the dominant form of computer storage for decades, but solid state drives are now taking over in many applications. Mechanical drives, also known as hard disk drives (HDDs), use platters coated with magnetic material to store data. Read/write heads on moving actuator arms access the data. This contrasts with solid state drives (SSDs) that have no moving parts and instead store data in flash memory chips.
Both technologies have advantages and disadvantages that make them suitable for different applications. When deciding between a mechanical hard drive and SSD, factors like cost, capacity, speed, reliability, size, noise, and heat should be considered. Evaluating these factors helps determine when mechanical drives are still a good choice and when SSDs are preferable.
Cost per Gigabyte
One of the primary advantages of hard disk drives is their low cost per gigabyte compared to SSDs. Although SSD prices have dropped substantially in recent years, HDDs still provide more storage capacity for the money. A 1TB hard drive can be purchased for around $40 while a 1TB SSD typically costs over $100.
This makes mechanical drives appealing for applications that require enormous storage capacity like data centers and NAS devices. The largest hard drives today have capacities up to 20TB while the biggest consumer SSDs are around 8TB. High density HDDs bring the cost per gigabyte down to under 3 cents while SSDs remain above 10 cents per gigabyte.
If you need massive amounts of storage on a budget, mechanical drives have a significant price advantage. The tradeoff is that accessing data on them is slower than SSDs. But for archived data or backups that are infrequently needed, the lower cost is often preferable.
Storage Capacity
As mentioned above, mechanical hard drives can offer far larger capacities than SSDs. Consumer hard drives are available up to 20TB while consumer SSDs max out around 8TB. Enterprise and data center drives go even bigger – HDDs up to 40TB and SSDs up to 30TB.
This higher capacity results from mechanical drives using multiple stacked platters coated in magnetic material. SSDs are limited by how many flash memory chips can fit on a board. Hard drive capacity keeps growing yearly as fabrication techniques allow squeezing more data bits onto each platter.
If you need to store huge amounts of data like home media, creative assets, or business records, mechanical drives offer unbeatable affordability. A 20TB hard drive provides enough room for over 5 million photos or 4,000 hours of HD video. SSD capacities top out at 2 million photos or 800 hours of video.
While SSD capacities will continue growing, hard drives will stay ahead for the foreseeable future. If your storage needs are beyond 8TB, mechanical is currently your only option unless you have an enormous budget.
Speed
The major tradeoff with the large capacities of mechanical hard drives is their slow data access speeds. SSDs have fast random access because they can read any data block instantly. HDDs require moving read/write heads to the correct area on the disk platter before transferring data.
Typical SATA SSDs have sequential read/write speeds around 500-550 MB/s while HDDs are in the range of 100-200 MB/s. More importantly, SSD random access measured in IOPS (input/output operations per second) is up to 100x faster than HDDs.
This speed difference makes SSD the clear choice in use cases like booting an operating system, launching programs, saving files, or loading game levels. An SSD allows a PC to boot in seconds rather than the minutes required by a HDD. Game load times also become exponentially faster with an SSD.
For frequently accessed data, mechanical drives feel unbearably slow compared to the instant response of SSDs. But for mass data that is infrequently needed, like archives or backups, the slower speed is acceptable to benefit from the lower cost per gigabyte.
Reliability and Lifespan
The moving parts in mechanical hard drives make them less reliable than solid state storage. SSDs have no moving parts and better withstand shock, vibration, and temperature extremes. HDDs fail more frequently with average lifespans around 3-5 years when used regularly.
SSD lifespans are affected by how much data has been written to them, a factor called write endurance. Top-tier SSDs last for up to 5 years of typical consumer use before degrading. Enterprise and data center SSDs designed for heavy workloads have higher write endurance, lasting 10 years or more.
Advances in mechanical engineering have improved HDD reliability tremendously over past decades. Modern drives in temperature controlled environments can operate reliably for years. But the unavoidable physics of spinning disks and moving heads means HDDs are still more prone to failure than SSDs. Their mechanical nature also makes data recovery expensive and difficult compared to SSDs.
For frequently rewritten data, SSDs provide much better reliability and lifespan. But for mass infrequently accessed storage, the shorter lifespan of mechanical drives is outweighed by the low cost.
Physical Size
The demand for ever higher storage capacities has led to mechanical hard drives becoming larger and larger physically. Today’s top-end consumer HDDs are up to 20TB, requiring 3.5 inch wide platters stacked in a case almost an inch thick. The largest enterprise drives measure over 15,000 cubic cm in volume.
In contrast, SSDs use tiny flash memory chips so even the largest options have compact 2.5 inch or M.2 form factors just millimeters thick. This makes them ideal for small devices and cramped computer cases where fitting a 3.5 inch HDD is difficult. It also allows creating massive external storage in a tiny package – a 50TB SSD is theoretically possible in a standard 2.5 inch portable drive case.
The bigger size and need for careful mechanical mounting of HDDs restricts their use cases compared to the easily fitted SSD. If physical space is limited, like laptops or compact PCs, SSD is likely the only viable option. Their compact design also provides more flexibility in device layouts.
But for desktop use or data centers where drive size doesn’t matter, the better TB-per-dollar value of mechanical storage makes them an efficient choice despite their larger form factors.
Noise and Heat
Spinning disks and moving actuator arms make hard drives less suitable than SSDs for quiet environments. Seek noise from the read/write heads moving and rotational noise from the spinning platters create audible disturbance. HDD noise averages around 20-30 dBA versus nearly silent SSD operation.
Mechanical drives also produce significantly more waste heat thanks to the energy required to spin the platters. A typical 3.5 inch HDD outputs around 6-8W of heat versus just 2-3W for an SSD. This requires more cooling which further increases noise since faster spinning fans are needed.
For desktop users, HDD noise and heat may be acceptable to benefit from the lower cost per terabyte. But in laptops or quiet workspaces, the silent running and lower temperatures of SSDs are preferable. Noise and heat also become major factors in dense data center deployments, giving SSDs the advantage.
But for cost-efficient archival storage, the noise and heat of mechanical drives can be mitigated by mounting them externally or in well-ventilated cases. Compared to the financial savings, the acoustic and thermal tradeoffs are often worthwhile in these scenarios.
Failure Recovery
When mechanical hard drives fail, recovering the data is an expensive process. Opening the drive in a cleanroom and transplanting the platters into a specialized recovery unit can cost thousands of dollars with no guarantee of success. HDD failures often damage the platters where data is stored, making recovery difficult and expensive.
SSD data recovery has much higher success rates and lower costs, typically around $500. The lack of moving parts means failed SSDs usually have the data intact. Installing the flash memory chips into a working unit allows recovering data from chips that are physically undamaged.
If the data stored on the drive is mission critical or high value, the better recovery rates from SSD failure helps justify the higher purchase cost compared to HDDs. For personal use this may not be a major concern, but businesses require considering the total cost of storage including recovery.
Hybrid Hard Drives
Hybrid hard drives (HHDs) combine an SSD with a mechanical HDD to get some benefits of both. A small SSD caches frequently used data while the HDD provides large capacity for mass storage. The SSD is invisible to the user – the hybrid drive appears as a single volume.
This hybrid approach works well in laptops and PCs, speeding up boot and app load times thanks to caching on the SSD. When larger files are accessed, the mechanical portion provides ample space. Hybrid drives are cheaper than full SSD storage but offer some of its performance advantages.
Hybrid storage is a good compromise that makes sense for many. If you need both speed and high capacity for a balanced budget, HHDs give you most of the SSD experience while taking advantage of HDD capacities. They are certainly better for system drives than pure mechanical hard drives.
Use Cases for Mechanical Hard Drives Today
While SSDs are now the better choice for most applications, there are still plenty of situations where mechanical drives have merits. Some examples include:
– Mass cheap storage for consumers – HDDs provide tons of capacity for storing personal photos, videos, music libraries, and game downloads with low cost per terabyte.
– Network attached storage (NAS) – Large multi-disk RAID arrays built from HDDs offer affordable storage for home media and backups.
– Archival storage – The low bit cost of HDDs makes them efficient for rarely accessed data like backups and archives. This includes cold storage in data centers.
– Desktop gaming rigs – A smaller but fast SSD for the OS and games, supplemented by larger but slower HDDs for storing files, media, downloads, and game libraries.
– Video surveillance storage – The enormous capacities required favor high density affordable HDDs for storing security footage.
– Big data and analytics datasets – Storing gigantic volumes of logged information benefits from HDDs’ high capacities and low costs.
So while SSDs are now the top choice for speed, HDDs are still better for maximizing capacity and storage density on a budget.
Conclusion
Mechanical hard drives still deliver great value for cost-efficiently storing massive amounts of infrequently accessed data. But for speed and reliability, SSDs are now superior for more performance sensitive use cases.
Here is a summary of when mechanical drives are still a good choice compared to SSDs:
– Need for high capacities over 8TB.
– Low cost per terabyte is important.
– Data will rarely be rewritten or erased after writing.
– Heat and noise are not concerns.
– Failure data recovery is not a critical issue.
But for general computing and gaming usage, SSDs provide a much better overall experience. Their instant access speeds, compact form factors, cooler running, and resilience are worth the higher cost for typical consumer demands. Mechanical drives are outdated as system and program storage, but still fulfill an important role providing huge affordable capacities.