Micron had a good run with 16nm planar (2D) flash, but now it's time for the company to jump on the 3D bus with Samsung and SK hynix so it can scale up density. In fact, Micron's 3D TLC NAND triples the density of today's 16nm planar flash. Looking to the future, that'll help lower SSD pricing and enable higher-capacity drives.
Perhaps you doubt that 3D NAND will cut the prices of SSDs in half, but we're certain this will happen in the next 12 months. Flash demand is low compared to what the foundries are cranking out. Unless companies are willing to turn their manufacturing lines off, the supply side will continue to grow. The easiest way to increase demand is to bring prices down until customers react.
Given the current climate, this is an odd time to introduce a new generation of flash. The hope is that higher densities will agitate the market and bring about a revolution that starts in the datacenter and trickles down to the desktop. Flash may finally achieve price parity with mechanical storage in typical notebook capacities. At the same time, enthusiasts should expect more options in the 2TB+ range. Within 48 months, we will have a client-focused 10TB SSD.
|Technology||Multi-Level Cell (MLC)||Triple-Level Cell (TLC)|
|Density||32GB (256Gb) die||48GB (384Gb) die|
|Process Node, Bit/Cell||3D, two bits per cell||3D, three bits per cell|
|Speed Grade||533 MT/s and 667 MT/s||533 MT/s and 667 MT/s|
|Page Size||16,384 + 2208 bytes||16,384 + 2208 bytes|
|Pages Per Block||1024||1536|
|Block Size||16,384 + 2208K bytes||27,888 bytes|
|P/E Cycle||3000 + read retry||1500 LDPC / 500 BCH|
Before we go into depth on Crucial's MX300, let's look at the 3D flash that will power the company's next generation of SSDs. There are currently eight part numbers for 3D MLC packages and they range from 32GB (one die per package) to 256GB (eight dies per package). Three packages feature FortisFlash. There are 10 different packages for 3D TLC and they range from 48GB (one die per package) to a whopping 768GB (16 dies per package)! Six of those packages utilize FortisFlash technology to enable higher endurance and boost burst performance.
FortisFlash added Dynamic Write Acceleration (an emulated SLC layer) to Micron's line-up, among other features. It was a good start, but the company made several advancements for its 3D flash introduction. For instance, this is the first 3D NAND to use floating gates, the technology both Intel and Micron have utilized for many years. Samsung and SK hynix employ charge trap technology. SK hynix tried its hand with floating gates, but found them difficult to work with at this scale. IMFT tells us the technology is worth the effort; it reduces noisy neighbor cell disruption and charge loss. While those conditions are not a problem with competing 3D flash at this point, as the stack moves up vertically and shrinks on the horizontal plane, the laws of physics impose some restrictions. IMFT thinks floating gate technology will provide an edge down the road.
The new flash utilizes four planes (quad plane) to interface with the flash processor. Samsung has used dual-plane 3D NAND to its advantage for several product generations. Micron should be able to level the performance field and be competitive once again with quad plane 3D NAND.
- "Pack in more capacity: get 3x the capacity of existing planar NAND products to enable up to a 2TB gum stick-sized SSD with our MLC 3D NAND and a 3.5TB gum stick-sized SSD with our TLC 3D NAND and more than 8TB with MLC 3D NAND and 10TB with TLC 3D NAND in standard 2.5-inch SSDs.
- Boost performance: achieve significantly higher read/write bandwidth and I/O speeds, as well as improved random read performance, thanks to our 3D NAND’s fast 4K read mode.
- Save power: reduce power consumption in standby mode thanks to 3D NAND’s new sleep mode features that cut power to inactive NAND die (even when other die in the same package are active)."
Crucial's MX300 is the first product to utilize IMFT's new 3D NAND technology, and the first model in that family is a limited-edition 750GB SSD. It packs two dies onto each package and puts eight packages on a PCB. The company plans to add drives to the MX300 line-up as manufacturing ramps up and it starts producing other package configurations.
Even though we saw a working demo at CES with Silicon Motion's 3D-compatible SM2258 controller, Crucial chose to use Marvell's 28nm Dean controller for the MX300. The 88SS1074-BSW2 surfaced in May of 2014, and is a four-channel processor with support for low-density parity check (LDPC). Crucial builds the firmware in-house to work with hooks embedded into its flash, allowing the company to realize better performance and endurance.
The 750GB MX300 we're testing today has 768GB of raw flash. It sets aside some space for background activities like garbage collection and wear leveling. Of course, we'll see 500GB and 1TB versions in the future. However, don't be surprised if there is no 128GB-class model outside of the embedded market. We know that Micron is going for multi-terabyte capacities, so SSDs are going to get bigger and leave some of those legacy sizes behind.
As you might have guessed given the four-channel processor, the MX300 is a mainstream product. Crucial says it achieves up to 530 MB/s sequential reads and 510 MB/s sequential writes. Random performance peaks at 92,000 read IOPS and 83,000 write IOPS with the aid of Dynamic Write Acceleration.
- Dynamic write acceleration
- Redundant Array of Independent NAND (RAIN)
- Multistep data integrity algorithm
- Adaptive thermal protection
- Power-loss protection
- Data path protection
- Active garbage collection
- TRIM support
- Self-Monitoring and Reporting Technology (SMART)
- LDPC Error Correction Code (ECC)
- Device sleep support
- AES 256-bit hardware encryption (TCG Opal 2.0 and IEEE-1667-compliant)
All of the advanced features carry over from previous Crucial SSDs. The MX300 doesn't offer anything new aside from its flash. It's also the first Crucial SSD with this Marvell controller. Even still, we're glad to see power-loss protection carry over, since it ensures data in the lower pages during a power loss. This form of power loss protection is geared to preserve data at rest and very few consumer SSDs offer this level of protection.
Pricing, Warranty & Accessories
The 750GB MX300 has an MSRP of $200. In addition to the drive, you get a key for Acronis TrueImage HD and a 7-to-9.5mm adapter bracket. Crucial's Storage Executive software was not available when we first tested the MX300. The updated software is now available and enables Momentum Cache, a DRAM buffer algorithm that increases disk performance.
The MX300 ships with a three-year warranty that is limited to 220 terabytes written. That endurance rating breaks down to 120GB of writes per day for five years.
Although it's only a small change, the limited edition 750GB MX300 ships in a silver box instead of Crucial's normal blue packaging. Similar to the company's other SSDs, there is no performance information printed on the box; you will have to do your homework before encountering this thing on a store shelf.
If the back label didn't give you a model number, you'd have a hard time distinguishing the MX300 from Crucial's two previous generations. The drive's chassis is similar to those coming from Taiwan and China. It is a screwless design held together with friction and tabs. The metal is very thin, though that shouldn't present a thermal problem since Marvell's four-channel controller generates very little heat.
The MX300 does use a printed circuit board that we haven't seen before. We suspect Crucial could shave a bit off one end, and it's possible that future 2.5" MX300s will incorporate optimizations to make them shorter.
Note the strips of capacitors between the controller and flash. They're supposed to keep the flash running long enough to save data in lower pages if power is lost. Most of us don't appreciate this until we need it, and we wish more SSD vendors would go to as much trouble to keep your information protected.
Controller & Flash
As mentioned, the star of this show is Micron's 3D NAND. The new flash comes up in the company's decoder as MT29F768G08EEHBBJ4-3R:B, but we couldn't find any information on Micron's website for that part number. We do know the density is 96GB per package, and each package contains two dies. This configuration facilitates FortisFlash technology for Dynamic Write Acceleration and other advanced features that increase endurance and boost performance. Micron will also sell 3D without FortisFlash in both MLC and TLC, though most of the part numbers we've seen include the extra features.