Hard drives are mechanical devices that use mobile heads to read data stored on disks (or disks) inside the device. The good news is that the technology of hard disks is quite advanced (it has existed in one form or another for about 60 years), so it does not cost much to implement it and therefore buy it. This means that you can get comparatively huge amounts of storage capacity for very little money.
But the same mechanical technology that makes hard drives a tempting value proposition causes other unfortunate problems. Dropping the unit could damage the internal mechanism and make your data inaccessible. And, again, hard disks are slow because they can only find their data by looking for them physically. The fastest external units you’ll find spin at about 7,200 revolutions per minute (or rpm), which is not really that fast these days. In comparison, desktop internal hard drives can have speeds up to 15,000 rpm.
On the other hand, SSDs store data in the flash memory and, therefore, can access them very quickly.
If you connect through a high-speed protocol such as USB 3.0 or USB-C, you will see the greatest advantages, but basically there is no case in which an SSD is not faster than a hard drive. And since the SSD units do not have moving parts, they are much more resistant and are better equipped to withstand the falls, bumps, splashes and abuse of daily use. This does not mean that they cannot be damaged or that they cannot lose data, but they have much more room for maneuver.
One disadvantage is that the memory used in these drives can only be written in a limited number of times, so your SSD may become unusable before a hard drive does, depending on how you use it. Another refers to traditional storage applications: Hardware-based encryption is, in almost all cases, a prohibited option for SSDs, since data is stored anywhere and everywhere, rather than in a just easy access chunk. And never, under any circumstances, you should run a defrag program on your SSD, since you will be using valuable writing cycles without any speed benefit.
Perhaps the biggest drawback of the SSD units is the price.
Do you want an external 2 TB hard drive? You can find one for less than € 75. An external SSD of 2 TB, on the other hand, will cost about 730 euros, and no, it is not a typo, since it would pay almost 10 times more for exactly the same amount of storage. (The same 75 euros that you could spend on the 2 TB hard drive will only provide you with an SSD of about 120 GB). If speed and endurance are critical to you, all that extra money is probably worth it. If they are not, you are wasting hundreds of euros unnecessarily. When considering the possibility of buying an external SSD, make sure you know what you are getting – and what you are going to do to your bank account.
The basics before buying an external SSD
Here are four key things to keep in mind when buying an external SSD.
Cost per gigabyte: The way to calculate the relative value in units like these is to make a simple division and calculate the cost per gigabyte based on the price of a unit determined on the day of purchase. Because the price of SSD fluctuates all the time, the relative value also changes all the time. As with internal SSDs, the way to weigh what you are paying is to divide the price of the SSD unit by the number of gigabytes of your capacity. Thus, for example, a portable unit of 120 GB produces a cost per gigabyte of about 83 cents; a unit of 250 GB of 100 euros, however, comes to 40 cents per gigabyte. At the time of writing this document, the external SSD units had a budget of about 25 cents per gigabyte, mostly models of second or third level manufacturers. Use this math to calculate the final price when you compare a large number of units.
Interface: Currently, most portable SSDs use USB 3.0 standard, although USB-C ports are becoming more common. This has no consequence on the speed, but it is a connector easier to plug. The ADATA SE730 external SSD drives and Samsung T5 portable SSDs use a USB-C (at the end of the drive) and the new USB 3.1 Gen 2 (at the host end) to achieve the fastest speeds possible. In our tests, however, neither of the two units was much faster in the new type of port. They are still very fast if they are connected to a USB 3.0 port. Some expensive external SSD drives come with Thunderbolt interfaces, but these are usually specialized models intended for use with Mac and Macbook computers.
Robustness: The degree of robustness varies from one disc to another, with the AD7A SE730, which is currently the market leader among the conventional price units. The IP68 certification is a good specification to take into account if you are serious about waterproof and dustproof units.
Carry weight: Most SSDs weigh a few grams. We support the retention loop in SanDisk Extreme units, since many of these units are small and light enough that losing them is too easy and expensive to commit.