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Crucial's MX100 solid-state drive reviewed

The peoples' SSD

In a lot of ways, Serial ATA SSDs have stagnated recently. Most new drives are just slightly different spins on their predecessors. They have similar controllers, lightly massaged firmware, and flash fabbed on finer fabrication processes. And different stickers on the outside. Can't forget the stickers.

We don't get big leaps in performance anymore, though. The limited bandwidth of the 6Gbps SATA interface is partly to blame, as are the inefficiencies of the associated AHCI protocol. Even with those handicaps, most decent drives are already fast enough for the vast majority of desktop applications.

None of that makes for a compelling storyline. There's one more thing, however, and it's a pretty big deal. SSDs are getting cheaper. Like, a lot cheaper. Just look at the release-day prices for the last four generations of Crucial drives:

Crucial's first 6Gbps SATA offering was the RealSSD C300, which arrived in 2010 with 34-nm flash. The drive rang in at over $600 for 256GB, making it an expensive luxury even for high-end PCs. Since then, each successive NAND generation has come with a substantial discount, culminating in the 16-nm MX100 that debuts today. Crucial's latest is priced at just $109.99 for 256GB.

Let me repeat that. The MX100 is priced at just $109.99 for 256GB.

That's only $0.43 per gig, more than a 5X decrease from the C300—and a 50% drop from the M500's introductory sticker one year ago. Quite the opposite of stagnation, don't you think?

Crucial's parent company, Micron, deserves much of the credit for plummeting prices. SSDs are getting cheaper because memory makers are using smaller process geometries to cram more and more gigabytes onto each silicon wafer. Micron aggressively pursues cutting-edge fabrication technologies, and Crucial enjoys the spoils.

The MX100 is the first SSD to use Micron's 16-nm MLC NAND. 16GB chips based on that process have been sampling since last year, and Micron claims they have "the greatest number of bits per square millimeter at the lowest cost of any MLC device in existence." We're waiting on details about the exact die dimensions and how they compare to the previous generation. For what it's worth, Micron says its 16-nm process is capable of squeezing "nearly 6TB" onto a single wafer.

Although smaller fabrication techniques are great for increasing bit densities, shrinking the process geometry typically decreases endurance. NAND wears out because writing data erodes the physical structure of the memory cells. That structure becomes more fragile as it shrinks, reducing the volume of writes the cell can tolerate. Packing cells closer together also increases the potential for interference from neighboring cells.

Micron isn't ready to talk about how many program-erase cycles its 16-nm NAND can endure. However, most desktop users will struggle to exceed the MX100's endurance specification. The drive is rated for 72TB of total writes, which works out to 40GB per day for five years. That rating matches the endurance spec for Crucial's M500 and M550 SSDs, both of which are based on 20-nm NAND. The MX100 has the same three-year warranty as those drives, too. Here's how the three families compare:

M500 MX100 M550
NAND 20nm MLC 16/20nm MLC 20nm MLC
Die size 16GB 16GB 8/16GB
Capacities 120-960GB 128-512GB 64GB-1TB
Controller Marvell 88SS9187 Marvell 88SS9189 Marvell 88SS9189
Sequential read 500MB/s 550MB/s 550MB/s
Sequential write 130-400MB/s 150-500MB/s 190-500MB/s
Random read 62-80k IOps 80-90k IOps 90-95k IOps
Random write 35-80k IOps 40-85k IOps 75-85k IOps
Total writes 72TB 72TB 72TB
Warranty Three years Three years Three years
Price (240-256GB) $114.99 $109.99 $168.99

The MX100 is essentially a replacement for the M500. It promises to outperform its predecessor at a lower cost, but there are a few caveats, including the fact that the M500 is much cheaper today than it was last year.

While the M500 is available in capacities up to 960GB, the MX100 is capped at 512GB. Folks who want more storage are directed to the higher-end M550, which goes up to 1TB, and to the M500 960GB, which hasn't been retired yet. It sounds like Crucial plans to keep the big M500 around for a little while longer.

At the other end of the spectrum, we should note that the MX100 128GB actually uses older 20-nm NAND. Only the 256GB and 512GB versions have the latest 16-nm flash.

All three drives are loaded with 16GB dies, which is a liability for the lower-capacity models. Modern controllers typically require at least 32 dies for peak performance. With 16GB per die, all the MX100s south of 512GB lacks sufficient NAND to exploit controller's internal parallelism. The 128GB and 256GB drives have lower performance ratings as a result.

Capacity Die config Max sequential (MB/s) Max 4KB random (IOps) Price $/GB
Read Write Read Write
128GB 8 x 16GB 550 150 80,000 40,000 $79.99 $0.62
256GB 16 x 16GB 550 330 85,000 70,000 $109.99 $0.43
512GB 32 x 16GB 550 500 90,000 85,000 $224.99 $0.44

Dropping to 256GB cuts the MX100's peak sequential write speed to 330MB/s. The 128GB variant is even slower, and it takes a big hit on random writes. The entry-level unit has higher per-gigabyte pricing than the rest of the lineup, too. No wonder Crucial only sent us the 256GB and 512GB drives. We've benched them both, and we'll see how they stack up in a moment.

The 512GB version is just as competitively-priced as its 256GB sibling, by the way. $224.99 is the lowest list price we've ever seen for a 512GB SSD.

Inside and out, the MX100 looks an awful lot like the M550. It has the same eight-channel Marvell controller and nearly identical features. To protect against data loss from physical flash failures, the MX100 employs a RAID-like redundancy scheme called RAIN. Onboard capacitors provide a measure of power-loss protection, enabling the drive to preserve in-flight data if the lights go out. There's hardware support for 256-bit AES encryption, too, complete with the requisite IEEE and TCG Opal compliance. The MX100 can also dial back its performance if temperatures get too toasty, a valuable capability for notebooks and small-form-factor systems.

The only thing that isn't on the menu is DevSleep, an extra-low-power mode designed for mobile systems. According to Crucial, the MX100 will respond to the command, and the feature is supported in the firmware. However, because Crucial hasn't seen a lot of demand for it, DevSleep isn't part of the drive's official specification.

DevSleep is geared toward mobile systems, which aren't really the MX100's native turf. Sure, the drive will fit into standard 2.5" notebook bays, but Crucial isn't making mSATA or M.2 flavors suitable for slimmer ultrabooks, convertibles, and the like. Instead of cranking out mini MX100s, Crucial will continue selling mSATA and M.2 versions of the M500. The M550 is also available in mini formats.

Overall, the MX100 covers all the essentials except utility software. Unlike most SSD vendors, Crucial doesn't offer an application to monitor health, optimize system settings, and track drive statistics. The firm makes matters worse by giving many of the drive's SMART attributes vague, vendor-specific titles that can only be deciphered with the aid of a separate decoder ring. The reallocated sector count is clearly marked, at least, but program and erase failures, error correction and RAIN recovery events, and total host writes are not. If Crucial isn't going to provide its own SSD utility software, it should at least stop making life difficult those monitoring their drives with third-party utilities.

Crucial redeems itself somewhat by shipping the MX100 with a download code for Acronis True Image HD 2014. The imaging software should come in handy for folks upgrading existing systems.

Now, let's see how the MX100 performs.