For several years since the invention of the first HDD (Hard Disk Drive) in 1956, they continued to reign supreme in the realm of data storage. HDDs are among the most popular devices for storing data on computers even today. However, their supremacy is now being challenged by the SSD (Solid State Drive) that promises to be speedier, quieter, and more efficient than HDDs. So, what are the differences between SSDs and HDDs and how do they stand up against each other? Let us understand this in depth.
An HDD or hard disk drive is a device used to store data on a computer. It consists of a platter that spins while in operation. A read/write head above this platter uses magnetism to record data on the platter. The speed of reading/writing data on this disk depends on the speed of its spinning. Standard speeds (RPM or revolutions per minute) vary from 5400–7200 RPM. Some HDDs can spin as fast as 15,000 RPM. HDDs are usually 2.5” or 3.5” in size.
An SSD or solid state drive is also a device to store data on a computer, but unlike an HDD, it does not contain any moving platters or mechanical read/write heads. Instead, it has a processor/controller and microchips. It used NAND-based flash memory to read/write information. This is a non-volatile storage technology which means the information is retained even when the power is turned off. Most SSDs also come in sizes similar to HDDs—2.5” or 3.5”. They are also available in a 1.8” form factor.
Many HDD manufacturers like Seagate, Samsung and Western Digital now also manufacture SSDs.
Comparing HDDs and SSDs
HDDs are known for their massive capacity and continue to offer a clear victory over SSDs in this regard. It is standard to expect HDDs of 500GB—2TB and above in modern laptops. HDDs of 10TB capacity are also available for desktops.
SSDs tend to offer much less capacity at present. Most laptops offer 256GB–1TB while 4TB SSDs are available for desktops[i]. This is because SSDs use new technology and are harder to manufacture. However, the cost of producing SSDs is falling rapidly, and it is probable that they will soon get bigger and cheaper.
Speed of Data Storage & Booting
SSDs score a massive win here. They offer tremendous read/write speeds for your data in the range of 200MB/s to 550 MB/s. The read/write speeds of standard HDDs are much slower; they are in the range of 50–120 MB/s only.
SSDs perform better not only in terms of the file-reading/file-writing speed but also the file-opening speed. They also have terrific boot-up times. On an average, SSDs can open your files up to 30% faster than HDDs[ii]. The average boot-up time with SSDs is only 10–13 seconds while HDDs take up 30–40 seconds. The difference may not seem discernible at this stage, but it adds up along with everything else. This is why many first-time SSD users are awed at how lightning-fast everything suddenly seems to be.
Cost of Storing Data
Those dizzying speeds don’t come cheap; SSDs are fairly expensive when it comes to the cost of storing your data. On an average, it will cost you $0.20 per gigabyte to store data in an SSD. Compare this with an HDD where it will take you only about $0.03 per gigabyte. It is because of this cost differences that SSDs haven’t yet become the dominant data storage technology.
Power Consumption & Efficiency
SSDs offer a distinct advantage in power consumption. This advantage is because they don’t have any moving parts and hence draw in less power than HDDs. While an HDD consumes more than 6 Watts during a full cycle, an SSD consumes only 3 Watts[iii]. In fact, the difference is impressive enough to produce an increase in battery backup by about 30 minutes.
On the reliability front too, SSDs tend to perform better. Since they have no mechanical parts, they are not as prone to damage as HDDs. They are also safe from harm by falling, vibration, and high temperatures. On an average, SSDs can operate smoothly in temperatures as extreme as 0°C –70°C. A typical SSD will run for 2 million hours without incurring failure. An HDD, on the other hand, has a standard failure rate of 1.5 million hours. It is vulnerable to failure if the computer suffers falls, crashes, vibrations, severe temperatures, or power fluctuations.
SSDs also benefit from the fact that they employ flash memory to store data. This technology insulates them from any potential damage caused by magnetism. HDDs are not safe from extraneous magnetic effects. Unwarranted magnetic fields might cause data loss.
Note: This does not mean SSDs do not fail at all; they do wear out over time. Whenever information is written to one of the storage cells of the SSD, that cell gets a little degraded. Over time, the cells are degraded to the extent that you cannot write/read anything further from the SSD. However, by the time this happens, you are likely to be considering changing your computer and drive anyway.
Also, SSD manufacturers employ two technologies to delay this degradation: over-provisioning and wear-leveling[iv]. The former guarantees that data is written evenly throughout the device so that no cells get worn more than the others. The latter ensures that the drive has more memory than is rated. This extra memory comes in handy to reduce the number of times data is written to a particular cell.
Noise & Heat Produced
SSDs are incredibly quiet. The absence of moving parts makes them silent performers. HDDs, however, function by spinning platters and this makes them noisy. You can often hear clicking sounds when the HDD is in operation, especially a few years down the line.
Likewise, the heat produced in SSDs is also negligible. While HDDs also don’t generate much heat, the difference is measurable. Remember that HDDs also tend to draw more power to function, and this adds to the amount of heat dissipated.
Data Security & Data Recovery
It is easy to destroy data from an HDD since it is magnetic media. However, destroying data on an SSD is not as straightforward. There is no direct solution to “sanitize” an SSD or make it fit and safe for reuse without compromising the sanctity of the data. You must destroy the drive itself with a device like the SSMD-2MM Solid State Media Disintegrator[v]. Another solution is to use encrypted SSDs. Once you delete the encryption keys, the stored data is useless. However, this approach also has a catch since it is not possible to be completely sure that the memory locations holding the encryption keys were entirely sanitized[vi].
The concerns with wiping data from an SSD currently make its data security questionable. However, manufacturers are working on resolving this problem. The rise of encrypted SSDs is reassuring. Many SSDs are self-encrypting with security features like “AES 256-bit encryption” (Advanced Encryption Standard)[vii]. AES is an internationally recognized specification for data encryption.
Similar to the complications of erasing data, it is also complicated to recover data from an SSD in case of losses. An HDD tends to show signals such as creaking noises when it is about to fail. But an SSD does not produce such noises. You have to watch out for strange error messages or frequent crashes. It is more expensive to restore lost data from an SSD. Hence, it is recommended to back up all your data, perhaps on an external drive.
Other Benefits of an SSD over an HDD
An SSD offers some more benefits when compared to an HDD:
- It eliminates the risk of disk fragmentation: With HDDs, data is stored on sectors depending on free space on the platter. After a time, blocks of data can get fragmented around the drive, and this ups the seek-time as well as the write-time. But SSDs employ flash memory to store data. Thus, there is no risk of fragmentation. In fact, experts recommend not to run the disk defragmentation command if you have a computer with an SSD.
- It is more lightweight and easier to carry: SSDs tend to weigh less than HDD, and this makes the laptop they’re fitted in lighter too. The 1.8” SSDs are especially sleek and travel-friendly[viii].
- It is better suited to high-performance activities: The true power of SSDs becomes evident when you perform demanding computing tasks such as rendering graphics, streaming live video, gaming, running stock market algorithms, and bioinformatics. Since SSDs use integrated circuits instead of magnetism to access data and don’t have any moving parts, they don’t get slowed down by friction. Note that installing an SSD will give you a major improvement in game load times. However, it won’t score any significant wins in the frame rate. To get higher frame rates, you need to upgrade your GPU (Graphics Processing Unit).
How to Choose Between an HDD and an SSD
Now that you know the comparative pros and cons of an HDD and an SSD, how will you make your purchase decision? Both storage devices have their merits, and the decision will depend upon your needs and budget.
- If you need a lot of storage capacity: An HDD will be a better pick as it can provide you with lots of data storage (10TB and above) at reasonable prices. However, SSDs with high capacity continue to very expensive.
- If you are on a budget: Here again, you will see a considerable cost win with an HDD. For example, while a 2TB Seagate HDD costs around $60[ix], a Seagate 2TB SSD is priced at around $399[x]. That’s more than six times as much.
- If you demand excellent performance: If your top priority is performance, an SSD will serve you much better than an HDD. It will deliver greater read/write speeds while producing minimal heat and noise and delivering excellent power efficiency.
- If you are using a laptop: Laptops stand to benefit the most from an SSD upgrade. SSDs make laptops more lightweight and portable and give a fillip to the performance. If you are using a desktop, you have other options to improve the performance. For example, you can install multiple drives such as an SSD drive for booting and an HDD drive for the rest of your data (that you don’t need as frequently)[xi].
What the Future Holds
Presently, SSDs are struggling to expand their data storage capacity while not letting the cost per bit of data rise exponentially. Recently, Samsung has unveiled a 30TB SSD that fits this gigantic storage space in a 2.5” device[xii]. This is abundant and more space to store audios, videos, pictures, documents, and any other material you need. However, the affordability of such a device continues to be a pain point. While Samsung hasn’t yet announced the price tag for this device, the 15.36TB SSD (launched by Samsung in 2016) cost around $10,000[xiii]. By contrast, a Seagate 12TB HDD, one of the largest HDDs available in the market today, is priced at around $410[xiv].
As time goes on, SSDs are likely to become the mainstream storage device at least for laptops and mobile devices. The advent of hybrid drives—a combination of HDDs and SSDs—has also opened up choices for the audiences. These drives are called SSHDs or Solid State Hybrid Drives. They offer the option of storing speed-intensive data such as the operating system files, gaming files, etc., on the SSD for quick access. The remaining data such as movies and pictures can be stored on the HDD. This is a win-win in both capacity and speed. Seagate offers a FireCuda hybrid drive (2TB HDD and 8GB SSD) for under $100.00[xv].
With SSDs becoming more and more mainstream and their costs falling, it is likely that they will soon become the dominant data storage technology. This will be a significant change as HDDs have ruled the roost for several years. But it will be a change that will prove beneficial across the table—from manufacturers to customers.