What Is SSD External Hard Drive?

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They are a form of flash memory and are developed as a replacement for hard disks. In recent years the use of SSD drives (solid-state drives) become very popular. This is due to the high demand for ultra-fast speed and high performance.

Flash memory was in use from a long time ago dating back to the 1970s and 1980s. But only the new developments improved the reliability and ease of use for this technology. These improvements enabled manufacturers to create solid-state drives to replace hard disks. They created internal and external SSD drives.

SSD drives are also known as SSD disk drive or even SSD hard drive. Although they don’t have any physical spinning disk.

Since they don’t have the limitation of mechanical disks and their latency, they have blazing fast speed. They are an attractive option as a primary or secondary storage device.

An SSD drive offers less noise, less power consumption, and more durability. Another advantage is that they are very resistant to shock, vibration, movement, and contamination and thus more reliable.

SSD drives are used in high-performance laptops and desktops, and in some servers. They are also used as secondary storage in mobile devices.

The SSD drives are becoming more and more affordable. They are desired by everyone. The extremely fast speed of an SSD and resistance to shock makes them a great choice. Like this SanDisk Extreme Portable External SSD which is water-resistant too.

They are especially great as an external drive. Also, the reliability of SSD drives has been improved. They are now as reliable as a hard disk drive and even more reliable.

External SSD or External Hard Drive?

There are some drawbacks to SSD drives though. Let’s go through them so that you can make an educated decision whether to buy an SSD drive or buy an HDD (hard disk drive).

  1. The cost per gigabyte of storage for SSD drives is significantly higher than mechanical disks. Thus an SSD drive of the same capacity as an HDD will have a considerably higher price than its HDD counterpart.
  2. SSD drives have a finite number of program-erase cycles, known as P/E. It is the number of writes and rewrites to the drive. When it reaches that limit the drive will start to wear-out. This creates limitations. For example, shredding files on an SSD and overwriting the files for security, will speed up the memory wear. This is not a practical option on SSD drives. This limitation compromises security and forensic examinations.
  3. When left without power for long periods, SSD drives slowly leak charge over time. A worn-out SSD drive starts losing data after one year (when stored at 30 °C) to two years (when at 25 °C). Extreme temperatures will speed up this process. New SSD drives have
    a data retention period of approximately ten years. Thus, SSD drives are not the right choice for data archiving.

Should I Buy External SSD or External Hard Drive?

Except for the price, which may not be affordable for some people, other limitations are under control due to recent developments. The warranty for SSD drives is reaching that of HDD. Like this SanDisk Extreme Pro Portable SSD, which has 5 years limited warranty.

Manufacturers compete on extending their SSD drives’ retention period. New SSD drives have much longer data retention periods. Also, these drives have higher P/E cycles, which makes them more durable than a hard disk drive.

To keep your data secure and private, instead of file shredding, you can use encryption. Either drive encryption or file encryption.

Don’t forget that hard disk drives have their own limitations. For example, they are very vulnerable to shock and vibration. Also if left without use for a few years, their mechanical parts can become clotted over time and the disks will not spin.

Each year SSD drives improve and become more and more reliable. With today’s SSD external hard drives and USB 3.0 fast speed, you can plug an external SSD drive to a laptop and it will be faster than the internal hard disk. The transfer speed of this SanDisk Extreme Pro Portable SSD is astonishing.

You can buy a laptop with small storage, and extend the capacity of the laptop with an external SSD. They could be used as the main storage.

If you can afford, an external SSD drive is a better option compared to an external hard disk drive.

Below is a comparison table between SSD drives and hard disk drives.

Important CharacteristicsSolid State DriveHard Disk Drive
Price per unit of StorageHighLow
Data RetentionLoses charge if left without power for a long time. New SSDs have longer retention period.Under ideal conditions (benign temperatures and humidity) can retain data for a very long time without power.
DurabilityHave a finite number of writes. New improvements increased the number of writes which makes SSDs very durable.
Vulnerable to power loss. Again newer models have power loss protection circuits.
High write speed causes heating. The newer models have thermal throttling to protect against over-heating.
They are vulnerable to shock and movement. The mechanical parts can fail.
But usually, they are durable. Support infinite read and writes.
High temperatures can shorten the life of HDDs. Under extreme temperatures cooling will be required.
Read and write speedsThe read and write speeds depend on the SSD drive and model.
Enterprise SSDs have read and write speeds of several gigabytes per second.
Newer models of Consumer SSDs have much faster speed compared to hard disk drives.
File fragmentation does not affect speed.
Read and write speeds depend on file fragmentation. The sequential read and write speeds are higher than random-access read and write.
Temperature rangeSSD drives can operate under a wider range of high and low temperatures.
For newer models, the temperature can be as low as -20°C or as high as 70°C. Outside this range the failure rate increases.
The HDDs can operate in the range of 0°C to 40°C. Outside this range the
failure rate increases.
Vulnerability to shock, vibration, movement, and contaminationVery resistant to shock, vibration, movement, and contamination.
Also not sensitive to orientation.
Very vulnerable.
Needs proper mounting and some models are sensitive to tilting.
Size and WeightVery lightweight.
SSD drives have the same form factor as HDD. That is because they are made to fit in the same slot which is for HDDs.
Can be made smaller in size.
Much heavier than SSDs and also larger in size.
Difference Between Read and Write SpeedsCheap SSD drives have a much slower write speed compared to its read speed.
Reliable brands and models have a write speed close to its read speed.
Generally, the write speed is slower than the read speed.
Power ConsumptionRequires less power compared to HDD, about half or third.
But SSD drives need to be connected to power.
Depends on the activity of the mechanical parts. Generally consumes more power.
Can be idle or go to stand by mode.

External SSD Drives and Connector Limitations

SSD external hard drives can be connected to a computer or a mobile device through different ports. Generally, these devices use USB ports or Thunderbolt port.

Let’s explore the limitations of each port and the challenges with the connectors of external SSD drives.

The USB interfaces have speed limitations. Below are the USB interfaces and their speeds.

  • The maximum speed of USB 3.0 Gen 2 is 625 MB/s
  • The maximum speed of USB 3.1 Gen 2 is 1250 MB/s
  • The maximum speed of USB 3.2 Gen 2×2 is 2,424 MB/s

If an external SSD drive has a USB connector and the specs say it is USB 3.0 compatible, that means its maximum speed will be less than 625 MB/s. And if the SSD drive is USB 3.2 compatible, the maximum speed will be less than 2,400 MB/s.

An external SSD hard drive can be as fast as 3500 MB/s. But none of the USB ports will be able to transfer that much data.

The only option for ultra-high-speed external SSD drives is to use Thunderbolt 3. It supports transfer speeds up to 5 GB/s.

SAMSUNG X5 Portable SSD and LaCie Rugged SSD Pro both support only Thunderbolt 3 and for the same reason stated above. These two external SSD drives are insanely fast.

The problem with this solution is that not all laptops and mobile devices support Thunderbolt 3.

And it creates compatibility limitations for the external SSD hard drive. The SSD drive will only work with some laptops and mobile devices.

When buying an external SSD hard drive, you must remember these limitations. If you need an ultra-fast SSD external hard drive, your laptop must support Thunderbolt 3 or USB 3.2 Gen 2×2. Even the fastest external SSD drive will be slow when connected to USB 3.0.

Some SSD external hard drives support all USB interfaces up to 3.2. The speed of these SSD drives will depend on the port. When connected to USB 3.0 the speed will be around 500 MB/s, with USB 3.1 the speed will be around 1000 MB/s, and with USB 3.2 the speed will be around 2000 MB/s.

This is exactly how the transfer speed of Seagate FireCuda Gaming External SSD varies with different ports. It is an ultra-fast external SSD hard drive with a USB connector.

Difference Between Actual Capacity and Advertised Capacity

Let me explain one important note here which will be helpful when buying external solid-state

Manufacturers use gigabyte (GB) and a terabyte (TB) as the units of storage, and megabyte per second (MB/s) as the unit of speed. They use 1 megabyte as 1,000,000 bytes, and 1 gigabyte as 1,000,000,000 bytes, and 1 TB as 1,000,000,000,000 bytes.

But the standard unit of 1 megabyte is 1,048,576 bytes (1024 x 1024) and the standard 1 gigabyte is 1,073,741,824 bytes (1024 x 1024 x 1024). It means that the advertised speed of an SSD will decrease if we calculate using standard units. For example, a 100 MB/s advertised speed would be 100,000,000/(1024 x 1024) which becomes 95 MB/s actual speed.

Also the storage will be less if we calculate using standard units. For example 1 TB (terabytes) of storage would be 1,000,000,000,000 / (1024 x 1024 x 1024) = 0.931 TB which is 931 GB.

And this is common to all manufacturers, not just one or two. That means if you see your computer showing the capacity less than the advertised number, don’t be surprised.

Or if your tests show that the actual speed of an SSD drive is slower than the advertised speed,
that is because they use their commercial units. So, it is kind of normal in the market.


Now you know what is SSD external hard drive. I have explained the important facts about external SSD drives. There are a lot of technical details that I didn’t include in this post. Those technical details will be of no use for most of the people.

If you are interested in technical details, you can search online and read more.

I only included information that will help you in buying an external SSD hard drive in the market. Any information that does not apply to the market is omitted.

Also, I explained the difference between an external SSD and an external hard drive. Now you can decide whether to buy an external SSD or external hard drive.

You may be interested to know What is the Best SSD External Hard Drive in the market. So, click on the link and read more.

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And if you have any questions or comments, please leave them below and I would be more than happy to help you out.

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4 thoughts on “What Is SSD External Hard Drive?”

  1. Thank you so much for this informative post. I have some external hard drives but I don’t have external SSD yet.
    Also, I appreciate you explain why the capacity of our external hard drives doesn’t match with what it shows on our computer if we check it’s real capacity. I thought it was a manufacturing defect or something.
    I like it if I buy an external SSD, besides price, durability, and temperature range, I will look for the 5-year warranty. Most products would only give a 1 to 2-year warranty.

    • Hi Ferra
      Thanks for stopping by and reading my post.
      SSD drives are a better option if you can afford them.
      When a manufacturer grants you a 5-year warranty, it means they are confident of their own product. The 5-year warranty is longer than the warranty period granted for hard disk drives.
      Definitely SSD drives are more durable than hard disk drives. And more convenient, because they are lightweight, small, and tough.
      Go ahead and buy an SSD drive and give it a try. You will enjoy its great features.

      Habiburrahman Dehzad

  2. Thanks for this post. I didn’t know much about external hard drives before reading this post. I had no idea that the capacity that is shown may not show the real capacity when we check on the computer. Is there a way to check than before you buy the product or does it depend on the hard drive itself?

    • Hi Ladia
      The difference between advertised capacity and actual capacity is common to all external SSD hard drives from every manufacturer.
      It is simple to understand. Generally, SSD hard drives come in specific capacities like 500GB, 1TB, 2TB.
      You can calculate the actual capacity for 500GB like this: 500,000,000,000 / (1024 x 1024 x 1024) = 465GB.
      Or you can use below pre-calculated numbers:
      – 250GB = 232GB
      – 256GB = 238GB
      – 500GB = 465GB
      – 1TB = 931GB
      – 2TB = 1.82TB or 1862GB


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