Most SSDs that use the M.2 form factor vaguely resemble a stick of gum.
The drives are less than an inch wide and typically about 3 inches long, and they can be installed directly onto a PC's motherboard, taking up far less space than the 2.5-inch and 3.5-inch drives they are quickly replacing.
But what happens if you'd like to upgrade an ultraportable laptop or an extremely tiny desktop PC whose motherboard doesn't have even 3 inches of space to share? Enter the Toshiba RC100 ($155 for 480GB as tested), a short, squat M.2 drive that's 1.6 inches long.
Although it uses cutting-edge technologies including 3D NAND and NVMe, it's far from the fastest M.2 SSD we've tested.
Still, it's relatively inexpensive and one of few options if you've got to fit an SSD into a very tight spot.
Tiny, Even for an M.2 Drive
SSD makers have largely settled on a 0.87-inch (22mm) width as the standard for desktop and laptop M.2 drives.
The aftermarket drives available and the accessible motherboard slots we've seen have all been that width.
While lengths vary a bit, the most common is 3.12 inches, or 80mm.
That means that most M.2 drives are referred to on their packages as M.2 Type-2280, derived from this standard length and width measured in millimeters.
The Toshiba RC100, meanwhile, is one of a less common breed of M.2 SSDs that are just over half the traditional length—1.6 inches (42mm), which results in the M.2 Type-2242 naming convention.
The Toshiba RC100 is the first drive we've tested that's this small, and it's one of the first name-brand M.2 drives with the latest 3D NAND memory-cell technology to be sold in this size.
There are a few obvious reasons why you'd want a smaller drive like the RC100, as well as a few (perhaps) less obvious ones why you'd want to avoid them.
The RC100's most significant benefit is that it can fit into places where other M.2 drives can't.
It's a bit like the approach you take when you're trying a new haircut: You can always cut more off if it's too long, but you can't add more hair if it's too short.
While a typical desktop motherboard with room for an M.2-2280 drive can fit smaller sizes, as well, a motherboard that only has room for an M.2-2242 drive usually can't fit anything else.
These types of motherboards typically show up in very small desktop PCs such as the Intel NUC ($329.99 at Amazon) or Shuttle XPC Nano, as well as ultraportable laptops.
The second benefit of an M.2 Type-2242 drive, especially if you're installing it in a laptop, can be energy savings.
Toshiba claims that the RC100 uses 70 percent of the active power draw of enthusiast NVMe drives.
Now, this won't translate into 70 percent longer battery life, since many other hardware and software factors affect how long a laptop lasts away from a power outlet.
It could still be a welcome ancillary benefit, though, especially if you plan to add the RC100 to an older laptop whose battery capacity has degraded over the years.
The main drawbacks to an M.2 SSD with a smaller physical size is reduced maximum throughput and capacity.
In very broad terms, and all else being equal, the longer the drive, the more memory chips of a given type you can stuff onto it, which means you can store more data (and access it faster, thanks to benefits from parallelism).
This is a major reason why the top M.2 drives we've tested are all M.2 Type-2280 varieties.
You'll see this reflected in the the RC100's price and capacity list: There's a 128GB drive for $60, a 240GB version for $80, and the 480GB configuration I'm looking at here, which lists for $155.
The fact that you can't order a RC100 above the 500GB capacity mark could be a deal-breaker.
Why? Some midrange laptops now come with 512GB SSDs, and many of the systems the RC100 will end up in don't have space for a second hard drive to serve as a repository for, say, large movie or image collections.
Still, 32 cents per gigabyte (for the 480GB drive) is attractive pricing for an M.2 NVMe drive.
The second limitation of the RC100's diminutive stature rears its head when it comes to data-access speeds.
Toshiba stems speed loss as much as it can by including the latest 3D NAND memory cell technology (though the RC100 uses the cheaper TLC variety) and employing the quicker PCI Express (PCIe) NVMe interface instead of the older, slower SATA or PCIe Gen 2.0 ones.
The result, as I found when testing the drive in PC Labs, is admirable speeds that are perfectly adequate for the types of tasks that you're likely to be performing on an ultraportable or tiny desktop, such as web browsing, watching HD videos, and editing text documents.
(For more on TLC and other SSD lingo, check out Buying a Solid-State Drive: 20 Terms You Need to Know.)
Partly because the drive uses cheaper TLC NAND, Toshiba projects that the 480GB version of the Toshiba RC100 will wear out after 240 terabytes written (TBW).
This TBW number is minuscule compared with high-capacity M.2 drives that use higher-quality MLC NAND such as the 2TB Samsung SSD 860 EVO (rated at 1,200TBW), but only slightly lower than the 512GB version of the SSD 860 EVO (which is rated for 300TBW).
Bear in mind that, to an extent, TBW ratings scale up as capacity goes up, again all else being equal; with more cells to write to, you have more means of sharing the write (and thus the wear) load.
Respectable Everyday Performance
The Toshiba RC100's sequential-read speed, as measured by our Crystal DiskMark 6.0 test, is 1,636MBps, while its sequential write speed is 1,124MBps.
This is an excellent result when compared with spinning drives or SATA-based M.2 or 2.5-inch SSDs, which top out at 550MBps or less.
But it's slower than the speeds offered by enthusiast-class PCIe NVMe drives meant for screaming gaming rigs or other power-user applications, some of which consistently record sequential-read speeds above 2,000MBps.
For instance, the Western Digital Black NVMe SSD recorded 3,129MBps sequential reads and 2,783MBps sequential writes on this test.
These sequential-read and -write speeds are important mainly because they describe a drive's theoretical maximum throughput.
In the real world, you'll rarely reach these maximums because everyday computing tasks are far from sequential.
Instead, opening and closing programs, starting up the PC, and other similar tasks access data in a random fashion.
Using the Crystal DiskMark test to approximate these conditions (4K file types at low queue depths), the RC100 managed 43MBps reads and 189MBps writes.
These numbers are in line with many other SSDs we've tested recently, including the Black NVMe, and significantly higher than SATA drives like the WD Blue 3D SSD ($119.99 at Amazon) , which recorded random reads of 36MBps and writes of 94MBps.
The upshot is that for the types of everyday tasks you're likely to be performing on an ultraportable laptop or mini desktop, the RC100 is perfectly adequate.
Perhaps nowhere is this more evident than on the PCMark 8 Storage test, which simulates web browsing, videoconferencing, and other tasks, and reports a single proprietary score.
The RC100 received a score of 5,055 on this test, and nearly every other SSD scores within a hundred points of 5,000.
See How We Test Hard Drives
The story is largely the same when it comes to the RC100's ability to transfer large files.
Using the AS-SSD 2.0 copy test, it copied a sample ISO file folder to folder on the drive at 1,125MBps, a sample app at 398MBps, and a sample PC game at 830MBps...
The ISO file copy speed, perhaps the most relevant for this test, falls in the middle of the pack.
The Samsung SSD 960 EVO M.2 achieved 1,605MBps on this test, while the SATA-based Samsung SSD 860 Pro recorded just 430MBps.
Solid, if You're Tight on M.2 Space
At a reasonable 32 cents per gigabyte for the 480GB version, and with everyday performance that rivals some NVMe drives that are much more expensive, the Toshiba RC100 is a good choice for upgrading the storage on a mainstream PC.
Add in its energy efficiency and small physical size, which allow it to fit in the M.2 slot of pretty much any motherboard, and the value proposition becomes even stronger.
However, a few potential quibbles to note.
The biggest is the limited storage capacity, which is even more limiting if your PC doesn't have any available 2.5- or 3.5-inch bays into which you can install a second, cheaper hard drive for extra capacity.
And while the RC100 does boast support for NVMe and uses 3D NAND, its theoretical maximum read and write speeds are far below what the flagship M.2 products from Samsung and Western Digital offer.
In short, it's nice that the Toshiba RC100 exists if you're faced with performing a storage upgrade on a laptop or desktop constrained by physical space on the actual M.2 slot.
If you have a full-size M.2 slot, however, you'll instead want to consider the WD Black NVMe, our current Editors' Choice for best M.2 SSD, or another full-length M.2 drive.
The Bottom Line
Bridging the gap between enthusiast PCIe and budget SATA M.2 SSDs, the Toshiba RC100 is a good choice for upgrading an ultraportable or a mini-desktop, or as a complement to a larger hard drive.
