SanDisk's Ultra Plus: Ballin' On A Budget
When you manufacture your own NAND, you can apply that special kind of knowledge liberally when the time comes to design your own SSDs. As one application engineer told me, "If I have a question about the flash, I can just walk down the hallway and ask somebody." Less-endowed companies in the storage business don't have that luxury. Sadly, that puts a lot of the really low-level optimization out of reach for much of the SSD industry, which is unfortunate because some of the most interesting developments occur in that flash netherworld these days.
In an adapt-or-die marketplace, some of the solid-state middle class are taking steps to fight back with strategic partnerships, firmware developments, and materials management to keep them competitive with the fabbed oligarchy. There is a shake-up coming, and we've already seen tragic departures from a market deep in the throes of consolidation.
At the end of the day, flash memory is the main ingredient of today's SSDs, and so the companies with their own NAND manufacturing hold most of the cards. As a firm without a fab, you really need some manner of competitive advantage or face the writing on the wall if you're making and selling SSDs. Either that, or hire Don Draper to come up with a wicked marketing strategy.
SanDisk is part of that gentleman's club with access to its own NAND fabrication facilities. Thanks to a joint venture with Toshiba, SanDisk has the manufacturing capabilities to crank out flash. And being a flash-only organization anyway, it has a fairly sassy intellectual property portfolio concerning solid-state storage. If the company's name doesn't resonate with you as an SSD purveyor, that's because most of its drives were historically sold to OEMs. The products we review are mostly part of a smaller retail segment, and for every drive we see, there are dozens more that end up in laptops, desktops, and servers.
Back in the early days, if you bought a laptop with a proper SSD inside, odds were good that it came from SanDisk. Until recently, if you bought a retail SSD, it probably wasn't one of SanDisk's. That's a situation the California-based company hopes to change, thanks in part to its stash of patents, some competitive engineering, and and a generous helping of NAND specialization. It doesn't even believe it needs its own controller. SanDisk does have a proprietary processor, but the first couple of retail efforts employed SandForce's logic. Like several other companies playing the controller field, SanDisk uses several SSD processors to better leverage its other strengths.
SanDisk's Ultra Plus is a fairly good example of that dynamic. Thanks to the company's NAND experience and some firmware prestidigitation, the Ultra Plus comes equipped with something SanDisk refers to as nCache. We first covered this technology in SanDisk Extreme II SSD Review: Striking At The Heavy-Hitters, but essentially, nCache is a system that allows each MLC NAND device to behave like single-level cell flash, resulting in higher performance, lower write amplification, and better endurance characteristics. SanDisk claims the effect is especially helpful with fewer outstanding commands, thus giving the Plus a bit more low-end grunt.
That's especially important as lithography shrinks, and features like nCache could help wring the best longevity from the Ultra's 19 nm Toggle-mode NAND. nCache itself isn't so new, but the technology certainly hasn't been a part of SanDisk's SandForce-based offerings. That controller doesn't allow the freedom to really optimize for deeper NAND integration. Without the ability to tweak every inch of SandForce's firmware, you have to adopt a competing controller (or design your own) to make features like nCache work. Marvell's SSD processors are just the opposite. Whereas with SandForce, you're locked into a firmware package, Marvell's controllers require you to create your own, letting the designer run wild as time and budget constraints permit.
The Ultra Plus is part of a design that originated from a lesser-known X110 SSD family, seen almost exclusively in OEM applications. At its heart, you'll find a Marvell 88SS9175 "Van Gogh Lite" controller. That particular piece of silicon is very much like the more traditional eight-channel 88SS9174 (used in products like Crucial's m4), except that it exposes just half the channels. The '9175 itself is used sparingly through the industry, residing in a handful of products from Lite-On and various custom applications.
Unsurprisingly, with only four channels to worry about, power consumption drops significantly, if not profoundly. That's fine and well, but drives like Intel's X25-V used half-channel designs too, and performance took a nose dive as a result. So, let's get this straight from the get-go: is SanDisk's Ultra Plus a victim of a silly budget-driven design disaster?
Fortunately, no. The Ultra Plus ships in three capacities: 64, 128, and 256 GB. Each is capable of impressive numbers at the respective size levels, too. We obtained all three to test, so that will be the final judge. But SanDisk ticks most of the feature boxes for a value-oriented drive.
|SanDisk Ultra Plus 2.5" SATA 6Gb/s SSD||64 GB Ultra Plus||128 GB Ultra Plus||256 GB Ultra Plus|
|NAND||19 nm eX2 ABL (MLC)|
|Interface||SATA Revision 3.0|
|Seq. Read/Write (ATTO)||520/155 MB/s||530/290 MB/s||530/445 MB/s|
|Random Read/Write (Iometer)||76/29K IOPS||80/33K IOPS||82/39K IOPS|
|Weight||38 g||39 g||40 g|
|Street Pricing||$65||$95 to $99||$165 to $175|
The first thing we notice is that those sequential read and write specifications aren't what we'd expect from a budget drive. The 64 GB model sports numbers that any ONFi-based 60/64 GB SSD should envy, while the 256 GB can conceivably write at a crushing 445 MB/s. Four-kilobyte random reads are quite spry as well, starting out at 76,000 IOPS for the junior member and escalating with die count. The only hint we get from the spec table that this SSD's origins are more humble than some of the newer high-end SSDs is comparatively lower 4 KB random write performance. Perhaps it all depends on how you're testing the drive.
SanDisk's 64 GB Ultra Plus currently sells for just north of $1/GB. That makes it about even with the most affordable 64 GB drives on the market, though availability isn't as robust as the two larger Plus models. The 128 and 256 GB capacity points are far more competitive online, and sale pricing can tip the value scale substantially in any one model's favor. It helps that there isn't much retail packaging to get in the way, since the box's contents are limited to the SSD, a 7 mm-to-9.5 mm spacer, and a short multi-language guide.