Intel SSD 525: Intel Goes 6 Gb/s With mSATA
Of the advances we've seen from solid-state storage over the years, perhaps the most under-appreciated is freedom to build SSDs in form factors that aren't married to mechanical rotational media. Obviously, 3.5” and 2.5” hard drives are well-established as standards. But in a world dominated by ever-shrinking devices, pushing conventional disks any smaller has been problematic. It's outright difficult to create a rocket-fast disk in a scant 50 mm.
The ability to store non-volatile data in any physical package you'd like means the mobile devices can keep information safe on microSD cards smaller than a postage stamp, and diminutive laptops enjoy storage options that slide right into a motherboard without a second thought to affecting Z-height. Even the largest servers benefit from higher storage density (not to mention obscenely favorable power-to-performance ratios) compared to spinning media.
After four decades, the hard drive market is almost entirely owned by two companies, and both physics and market forces work in tandem to make differentiation a headache.
That isn’t to say that the SSD landscape is so entirely different. A small cabal of fabricators crank out virtually every bit of NAND (pun intended) extant, while LSI SandForce and Marvell provide the lion’s share of controller shipments. Fortunately for us, there’s more than enough variety to keep things interesting. New controllers, new interfaces, and advanced flash manufacturing help push solid-state storage away from the considerations we make while evaluating legacy media. Smaller form factors are finally coming into their own.
SSD revenue is still a rounding error for Intel. Instead, the company's storage products are important for driving sales of its bread-and-butter offerings. Conceivably, they'd help take a bit of the sting out of sagging PC sales. A good example is Intel's 2.5” and mSATA-based SSD 311 drives, released alongside its Z68 Express platform to illustrate its caching features. Elsewhere, the SSD DC S3700 enterprise drives are shipping in 1.8” flavors to put more juice in dense blade servers (another market where Intel's high-margin server components shine a little brighter complemented by solid-state storage).
Now, Intel is dropping out of the motherboard business to focus on a future dominated by alternative form factors. And even though Ultrabooks haven't been as successful as the company hoped, a world of x86-powered tablets, NUCs, and all-in-ones necessitate NAND-driven storage. With that in mind, Intel recently introduced a new family of 6 Gb/s mSATA-based SSDs to address growing demand for pint-sized drives.
Meet The SSD 525
Today, we have a quintet of SSD 525 drives (code-named Lincoln Crest) that allow us to examine performance at the 30, 60, 120, 180, and 240 GB capacity points. Despite its new name, the SSD 525 is still mostly an SSD 520 in an mSATA form factor and Intel's LLKi firmware on top. Originally, that drive was the first fruit of a partnership between Intel and SandForce, which debuted a year ago, was driven by the SF-2281 controller, and featured specialized firmware. The SSD 520 included highly-binned synchronous 25 nm MLC flash from Intel's own fabs, and Lincoln Crest keeps the same tradition going.
The 30 GB model is particularly interesting to us, since it’s heavily outgunned, packing only four 64 Gb dies. With just half of the SF-2281’s channels populated, it looks to be the single-core Celeron of this family. Given how poorly 60/64 GB drives wielding eight 64 Gb die have performed in the past, we're definitely curious to see what the runt of the litter can do for its fairly hefty $53 MSRP.
Each member of the SSD 525 line-up wields Intel's 25 nm synchronous ONFi 2 flash from its private stash of highly-binned NAND. Due to mSATA's physical dimensions, four or less package emplacements are necessary, meaning capacity is restricted based on current die packaging. That still leaves all the most popular capacity points covered, leaving room for the interface to evolve as 128 Gb die become more popular.
As MLC (and TLC) NAND manufactured using the latest technology nudges endurance to new lows, it's increasingly difficult to get flash rated for 5,000 P/E cycles on the consumer side. Intel's SSD 525 might not be that adventurous, but it does have longevity going for it at least. And in a 50 mm travel size, too.
|Intel SSD 525 (mSATA)||Total Flash||Die Count||Channels/Interleaving||NAND Part No.|
|30 GB||32 GB||4||4x1||29F64G08LCME2|
|60 GB||64 GB||8||8x1||29F16B08MCME2|
|120 GB||128 GB||16||8x2||29F32B08NCME2|
|180 GB||192 GB||24||6x4||29F64B08PCME1|
|240 GB||256 GB||32||8x4||29F64B08PCME1|
The SF-2281-VB1-SDC is an eight-channel controller. Simply populating each of the ASIC's channels doesn't mean all that much; die interleaving is more important. Interestingly, the 30 and 180 GB models don't utilize all eight channels. The 30 GB version populates just four with no interleaving, while the 180 GB varietal uses six channels. Each discrete channel needs a couple of die to spread operations across, lowering latency and increasing speed. In the -2281, four-way interleaving offers optimal performance. So, referencing the table above, the 240 GB drive should facilitate peak performance with all eight channels individually firing across four die.
In the case of the 30 GB SSD 525, we're expecting it to be severely hamstrung. The 180 GB model should nip at the largest 525's heels, though. For now, it's important to note that the 180 GB's 24 dice spread over six channels with 4x interleaving is practically identical to using all eight channels with 3x interleaving. The point? Just because each channel isn't being used doesn't mean speed is going to suffer. It all comes down to interleaving in modern controllers, especially the scalable SF-2281.