Yesterday I started to talk about some of the top USB disk drives like small-sized flash memories (aka memory sticks) and external USB hard disks (some of which are so very large, offering plenty of terabytes for even better prices than SATA disks).
But that is NOT all about USB disks! Solid state drives, also known as SSDs, have their own room in the USB Palace :). We will notice that there are some very fast USB portable drives, that will best match the rated speeds for their USB versions (currently 3.0 and 3.1 are the most recent standards).
USB SSDs can also be named “portable SSD” or external SSD. I am not saying that all the external SSDs in the world use the USB interface, but this article is means to address the fastest USB drives. We will also understand why SSDs deserve to be called “the fastest”.
And I owe you an article about these USB solid state drives, because once we start to speak about a certain subject we should tell it all! We are going to know better about how USB SSDs work, then we will also see some of their best, which is Top USB SSD drives!
USB SSDs are still Flash-based, but faster than sticks
Like memory sticks, that are a kind of small-form-factor flash memory, and like internal SSDs (SATA, PCI-E), USB SSDs are also based on the non-volatile NAND flash memory, that keeps data also when PCs are turned off.
But this does not mean that USB SSDs are just a kind of “brother/sister drives” to USB pen drives aka memory sticks. Their internal structure is different, and their NAND memory is not constructed the same way!
In the SATA area, that is inside the computer, we get HDDs and SSDs, and we already know SSD drives are faster. This truth applies also to the USB world, where the USB SSD is faster than both the USB HDD and the small flash drive we can hold with fingers. SSDs do not refute their “I am the fastest!” character! And they are also the most expensive USB drives.
But why are USB SSDs faster and more costly than memory sticks, since both drive types base on the NAND flash memory? What is different in SSDs?
Well, we need to understand two terms that are specific to the NAND flash memory. These are single-level cell (SLC) and multi-level cell (MLC). I already offered some explanations about how SSDs work in a previous article, but let’s understand these strange words now (or again)!
We can imagine the internal storage space (i.e. that flash memory) of an SSD as a skin. Like our skin. Biology teaches us that our skin is divided into cells. So the memory of an SSD is likewise divided into memory cells, just like hard disks have their storage space organized as clusters and sectors. It does not matter whether the SSD uses the USB interface or SATA/PCI-E, memory cells are always its basic units of storage. And these cells are actually transistors – this is their equivalent name in SSDs.
These cells can have different modes of organization, when it comes to how many bits of information are stored in each cell. And each bit of info can have two states: 0 and 1. We know that from binary mathematics.
Depending on the number of data bits that are stored per cell, we have the two terms above.
Single-level cell means that each transistor takes care of one single bit of information, while MLC can alternatively mean 2, 3, 4, and in the coming future even 5 such bits per cell.
Moreover, there’s a market convention that puts the equal sign between 2-level cell and multi-level cell (MLC = 2 bits/cell), so let’s know how to differentiate these terms. So MLC can mean 2 to 5 bits per cell, but also exactly 2 bits per cell. Triple-level cell, quad-level cell, and penta-level cell (TLC, QLC, PLC) may be used to describe the rest.
Multi-level cell ensures higher data density per cell, meaning that less cells (transistors) are needed for every gigabyte of flash memory. This makes the price of that drive more affordable, but the higher the data density is, the slower the data speed will be. After all, that transistor (cell) will deal with more bits and their 0/1 states, it’s like carrying more bags when shopping. And there’s another drawback: the program/erase cycles (i.e. how many times we can write and delete data) are fewer than when using SLC. Think about 1000 to 10000 such cycles for MLC.
Single-level cell technology, on the other hand, provides SSD cells with smaller burdens (just one bit), data speeds will be greater in this case, but of course there will be more transistors needed for each gigabyte of storage, and prices will be higher. But we can write/delete data for more times when using SLC (50000 to 100000 program/erase cycles).
So, SLC = high data speed = expensive price = the skin has many cells = we can write more.
MLC = slow data speed = less cells = it’s better not to write often = it is cheaper!
Back to our USB flash drives versus SSDs, guess what types of NAND memory do these devices use?
It is stated that SLC SSDs are preferred in server and high-end environments, while MLC ones are targeted for mainstream users. Also, MLC has improved in the past years. But USB SSDs are generally faster than thumb drives.
USB sticks are built from multi-level cell NAND memory, while USB SSDs, if they don’t use SLC, at least they should have some better MLC flash memory models, explaining why SSDs are faster than sticks. Lower cell levels also give us freedom for more writing activities – and SSDs have clearly this advantage. Of course, there’s an extra price to pay for these differences.
A different explanation for “Why USB SSDs are faster than USB sticks” is the internal controller. The controller of a stick has a single channel (allowing it to talk to just one flash chip at the same time), thus limiting the speed of the data. Some sticks can have multi-chip addressing, but generally their controllers and chips do not have a great quality, in order to keep the costs low. By contrast, SSDs are manufactured with more care: their controllers are able to address a larger number of chips (like 8 or more) simultaneously. And SSDs may have DRAM caches for retrieving data faster, or at least some SLC caches (here the cell level comes again!), so that USB SSDs not only have a solid state, but also a solid reason to move faster than sticks :).
Speaking of the internal controller – sticks have a small micro-controller, while SSDs have a complex controller (as a matter of fact, it is an embedded processor) that needs to address problems like data encryption, bad block mapping, read/write caching, wear leveling (this one is about how many write/delete operations have been performed, see those thousands of cycles above), and more.
And finally, let’s face another SSD-specific term: the 3D NAND. Manufacturers tried to put the transistors (cells) very close to each other on a flat surface, for reducing sizes and increasing capacities, but drives became less reliable because of this closely-spacing strategy, so they had to place the memory cells in the top of each other (vertically) for increasing the drive capacity without quality losses. Naturally this led to a vertical placement of the cells, hence the 3D NAND name, also known as Vertical NAND or V-NAND, which is actually the latest technology for flash memories.
Very good examples of USB SSDs
Now that we know some more about how USB solid state drives work and what makes them fast, let’s see how far they can get with capacities, speeds, and prices!
The Samsung T5 Portable SSD is a suite of four different products (250GB, 500GB, 1TB, 2TB). So you have where to choose from, and if you are curious and can afford, then you can get a 2TB USB SSD that supports the latest USB generation, the 3.1 “Gen 2” one. All four items support read and write speeds up to 540 MB/s (well, if we multiply this by 8, we aren’t exactly getting 10 Gb per second, maybe the next years we will see faster drives), but this is still quite impressive and comparable to what SATA SSDs can do for us!
Samsung T5 SSDs are not as tiny as memory sticks are: their dimensions are 7.4 x 5.73 x 1.05 cm, and their weight is 51 grams (though the exact weight can vary by capacity, so the 1 and 2 TB parts might be slightly heavier).
These SSDs are backwards-compatible with USB 3.0 (aka 3.1 Gen 1) and 2.0, so don’t worry if your PC doesn’t support the most recent USB versions (but in that case expect the speeds to be lower). The smaller-capacity 250GB and 500GB SSDs are blue (Alluring Blue), while the “terabytic” ones are black (Deep Black). They also support AES 256-bit hardware encryption. Their warranty is 3 years long.
You need only a compatible USB cable for connecting such an SSD to your desktop/laptop PC. See their specifications here:
As for the prices, the 2TB part would normally cost almost $500, but with a generous discount that may be only around $300. However, it’s still much money. But the discount makes it more affordable than a NVME SSD of 2 TB.
And remember: it’s two terabytes. What can we store within two TB of space? Your family & travel photos would find a pretty generous space on such a drive. Along with your preferred music as well. While it’s also fast and portable. Well, even the smaller models would provide great performance and enough space for much personal stuff!
Check their prices here:
Discounts are welcome, but life teaches us that we cannot rely on discounts for a very long time. Basic price has to be paid attention to. And maybe some of you want great performance and storage for not that much money. So let’s see another suite that is a good candidate to “Best value”.
The Seagate Fast SSD also comes with four capacities, same as above: 250 GB, 500 GB, 1 TB, and 2 TB. The right version of the USB interface is 3.0, and their read/write speeds are 540 MB/s and respectively 500 MB/s, almost the same as the Samsung drives above. But this time we are dealing with the 3.0 generation, which in theory allows speeds up to “only” 5 Gbps per second, and multiplying by 8 the 540/500 numbers above, we get pretty close to that limit. So we must say that Seagate Fast SSD honors its USB 3.0-gen very well.
They are compatible with USB 2.0 ports too, but of course speeds would have to suffer. Seagate says that the required operating systems are Windows 7 or above, and Mac OS X from 10.9 on, but that does not convince me that they cannot be used with Linux systems as well.
Their dimensions are 94mm * 79mm * 9mm. It is also stated that these SSDs are shock-resistant (they may be accidentally dropped on the floor and still work), but of course it’s better not to try our luck and abuse the drives :). Seagate also provides a folder synchronizing software for keeping your most important files up-to-date while stored on a Fast SSD.
Their colors are Grayish Aluminium.
The 2TB SSD can be found with a price of less than $350 (this time with no discount), but it’s around 30% cheaper than the Samsung 2TB SSD without discount. After all, we know that Seagate products have relatively affordable prices.
Visit the manufacturing site here:
Both the product families above provide portable external SSDs using USB, but their physical sizes are liken to the 2.5-inch internal SSDs we know. However, there are also USB SSDs whose dimensions remind us of memory sticks.
The ADATA SE730H external SSD drives were launched in 2017 and they were of course reviewed on the Internet, but initially they came only as 256 GB and 512 GB drives. Now there is also an 1TB ADATA SE730H SSD, and they are smaller than the models above.
They measure 7.1 * 4.3 * 1.0 cm (actual dimensions may vary by product though, but they are still small), provide up to 500 MB/s read/write speeds, and belong to the USB 3.1 Gen 2. They are of course lightweight: just some more than 30 g.
So, we get fast and portable 1TB drives that are so small! We can take such a piece anywhere and store a lot of files on it (music, movies, photos, the OS to boot…). Also, they are said to be waterproof and shockproof, so if you happen to accidentally drop your ADATA 1TB SSD in the water and take it back quickly, it means that it should still work.
Their internal technology is 3D TLC (Triple-level cell) NAND Flash memory, that is a sort of multi-level cell.
These SSDs also require a USB cable (as a matter of fact, it’s called USB type C, provided also for models above). Although they may physically look similar to pen drives, we cannot just plug them into a USB port, but still need a cable. These ADATA small pieces up to 1TB are said to work under Windows, Linux, OS X, and even Android (from 5.0 on), thanks to that USB type C cable.
Imagine your smartphones support USB On The Go (OTG) feature – that makes them able to support an external disk drive that’s connected to them. I guess that this way the fact that these ADATA external SSDs support Android really makes sense.
USB power is almost everywhere nowadays – even outside the PCs, we may find it in tablets, smartphones, outlet chargers for our devices… There is plenty of things USB can do for us!
The 1TB SSD from ADATA is not so cheap either, although it has just one terabyte. You should expect to spend over $150 on it. Of course, its smaller-capacity brothers are more budget-friendly.
If you are curious to see this SSD, you go here:
and on their site:
Solid state drives are widespread in our days. There are PCI-E NVME SSDs, SATA-III SSDs, USB SSDs, Thunderbolt SSDs (I have to write about Thunderbolt too).
External USB SSDs may not be as fast as NVME SSDs, but the best of them compare very well to SATA SSDs. And they offer generous capacities, at least up to 1-2 terabytes, while having also the great advantage of portability, unlike other SSDs. The prices for top USB SSD drives may be salty, similar to NVME SSDs’ ones, but let’s not forget another thing that makes USB devices special: portability.
We also know that while USB SSDs and pen drives share basically the same type of memory (NAND), there are some remarkable differences that boost the SSD performance. And speaking in general: USB is so widely available that we see them in non-computer environments too, like connecting an external USB drive to a modern phone! Device portability empowers us pretty much.
Please feel free to leave your opinions as usual, and spread the content if you find it interesting! I will get back and there will be improved contents, along with other interesting articles about PC stuff.