The MacBook’s SSD: NVMe & an Apple Developed SSD Controller?

To be honest, prior to receiving the MacBook I wasn’t expecting anything particularly interesting for the laptop’s SSD. While we haven’t seen both sides of the MacBook’s logic board, and as a result can’t say with certainty how it’s laid out, from the side we have seen it's clear that we’re also looking at a soldered SSD. Which makes a lot of sense, as Apple choosing to save every last millimeter means a M.2 SSD would be out of the question, and meanwhile Apple has plenty of SSD suppliers to choose from, even for soldered designs. Consequently what I was expecting was a Samsung or Toshiba PCIe SSD soldered on to the logic board, similar to the SSD selection of Apple’s other devices.

So imagine my surprise when I opened up the System Profiler to see under the hood, and found not one but two unexpected things. First and foremost, a new section was available under the Hardware tree called NVMExpress. Second of all the device listed under NVMExpress has a model number prefix we’ve never seen before; not Samsung or Toshiba, but rather an Apple-ish “AP”. Clearly the MacBook’s SSD was going to be a much bigger deal than I first thought.

We’ll start with the NVMExpress heading. Short for Non-Volatile Memory Express, NVMe is a new software interface/protocol designed specifically for PCIe SSDs, and designed to complete what has been a two-part transition from SATA SSDs to PCIe SSDs.  NVMe replaces AHCI (Advanced Host Controller Interface), which dates back to 2004 and was designed with hard drives in mind. While that doesn't prevent its use on SSDs, AHCI is more optimized for high latency rotating media than low latency non-volatile storage. As a result AHCI can't take full advantage of SSDs, particularly PCIe SSDs with their high bandwidth links, leading the storage industry to develop a software interface that abolishes the limits of AHCI.

NVMe in turn is built specifically for SSDs and PCIe, and as software interfaces usually live for at least a decade before being replaced, NVMe was designed to be capable of meeting the industry needs as we move to future memory technologies (i.e. we'll likely see RRAM and MRAM enter the storage market before 2020).

  NVMe AHCI
Latency 2.8 µs 6.0 µs
Maximum Queue Depth Up to 64K queues with
64K commands each
Up to 1 queue with
32 commands each
Multicore Support Yes Limited
4KB Efficiency One 64B fetch Two serialized host
DRAM fetches required

The biggest advantage of NVMe is its lower latency. This is mostly due to a streamlined storage stack and the fact that NVMe requires no register reads to issue a command. AHCI requires four uncachable register reads per command, which results in ~2.5µs of additional latency. Another important improvement is support for multiple queues and higher queue depths. Multiple queues ensure that the CPU can be used to its full potential and that the IOPS is not bottlenecked by single core limitation.

Ultimately NVMe was designed first and foremost for the enterprise market, but client workloads benefit as well, though not by quite as much. For client workloads NVMe still brings with it a reduction in latency, and as our own Kristian Vatto has been keen to point out, even moderate improvements in performance result in increased battery life and that's what NVMe will offer. Thanks to lower latency the disk usage time will decrease, which results in more time spend at idle and thus increased battery life. There can also be corner cases when the better queue support helps with performance.

It’s just in the last year that we’ve seen NVMe deployed into PCIe SSDs, and those of course have been initially released on to enterprise SSDs. Meanwhile in the consumer space, due to boot issues with NVMe – you need a motherboard as well as OS that can handle booting from NVMe – SSDs are still almost entirely AHCI.

Which is what makes Apple’s situation so interesting. With such extensive control over their hardware and software alike, Apple has gone ahead and started shipping NVMe drives, beginning with the MacBook. For the MacBook in particular it’s a soldered SSD so Apple doesn’t need to worry about replacement parts or end-user modifications, so this if anything is the safest way to roll out NVMe.

Ultimately compared to going with PCIe SSDs a couple of years ago, the move to NVMe isn’t quite the same great step. But it’s none the less an important step for Apple as it indicates they’re ready to start shipping NVMe devices, and consequently reaping the performance and battery life benefits.

Shifting gears, let’s talk about the SSD controller. Along with supporting NVMe, Apple’s SSD also supports a fairly wide PCIe x4 connection. Somewhat surprising it’s only clocked at 5 GT/sec (PCIe 2.0 speeds), but it’s unclear at this time whether that’s a controller limitation or an intentional design decision by Apple (update: It's a Core M limitation). Even at 5 GT/sec, an x4 link means there’s 2GB/sec of bandwidth in each direction, which is far higher than how quickly the SSD can read or write.

But the big mystery right now is who made the SSD controller in the MacBook. As we’re not allowed to disassemble our review samples (as badly as we’d like to in this case), we’ll have to wait on the crew at iFixit to get around to tearing down the new MacBook, and in the meantime we’ll have to work off of what information we can gather through software.

In short, while Apple goes through a fair bit of effort to hide the manufacturer of their SSD – Apple SSDs are routinely labeled as “Apple SSD Controller” and “APPLE SSD” – they have never before completely hidden the manufacturer. In the 2013 MacBook Air 13” for example the drive model was “SM0256F”, indicating that it was a Samsung SSD. However for the MacBook there are no identifying labels to be found. The model is “AP0256H”, nor do the revision or serial numbers point a finger at any particular OEM.

At this point I’m not ready to rule out this being a better hidden OEM SSD, but the number of OEMs with NVMe capable client controllers is a very small list, so there aren’t too many options here. Of note, both Marvell and Samsung have NVMe capable client controllers, so this may yet be one of theirs’.

But for the moment at least I suspect we’re looking at an Apple semi or fully custom SSD controller. Why Apple would want to go this route is still something of a mystery to me, as they don’t necessarily have much to gain other than the obvious change of bringing control in-house, but here we are. Apple does have plenty of internal resources to develop SSDs, including the assets they gained in their 2011 acquisition of Anobit, so from a technical perspective Apple developing an SSD is not too hard to believe.

Though regardless of who’s behind it, the end result is a very fast, very capable controller that’s being used to drive the 256GB and 512GB SSDs available to the MacBook.

Update: 04/15/2015: iFixit has completed their MacBook teardown and posted the photos, including photos of the logic board from both sides:


Image Courtesy iFixit

Based on iFixit's teardown, we can see their sample is equipped with Toshiba MLC NAND, 128GB per side, 1 package per side. However of greater interest is the chip bordered in orange, which based on the fact that it has multiple markings we believe to be the SSD controller, assembled in a Package-On-Package (PoP) fashion. The number we can decode is a part number for a 512MB Hynix LPDDR3 memory module; the other number we cannot decode at this time. Multiple markings in this fashion is a tell-tale sign of a PoP chip, and having the SSD controller and its DRAM on-package with each other and located right next to the NAND chips makes a ton of sense, especially in such a cramped design. That said, it means we aren't going to get to see the SSD today; but it also confirms that this is not an off-the-shelf SSD controller since someone had to go through the extra step of PoPing it. The big question remains whether Apple has simply packaged up one of their regular suppliers' controllers, or if this is some kind of semi/fully-custom Apple controller.

Diving into our benchmarks, we’re going to have to take a slightly higher level look at the SSD than usual, at least for now. Being fully soldered on to a Mac limits our flexibility to more deeply test it unformatted (and not as a boot drive), and furthermore Futuremark’s PCMark 8 Storage benchmark refuses to behave. So for the moment we have our sequential and random benchmarks from iometer, which can give us a good idea of what sustained read and write performance looks like.

128KB Sequential Read (QD1)

128KB Sequential Write (QD1)

128KB sequential performance starts off very strong. The MacBook’s SSD is able to easily surpass any of our other Macs’ sequential read performance, delivering 665MB/sec under iometer. Meanwhile sequential write performance doesn’t quite top a 128GB SSD from a 2012 MBA 13, but otherwise it’s ahead of our other MBAs and rMBPs at 459MB/sec.

It’s actually a bit surprising that the SSD does this well here. Even with PCIe and NVMe, we’re looking at a highly integrated soldered solution, and I expect Apple has kept the number of NAND channels down in order to try to further conserve space. So to top our Mac charts in this fashion is unexpected and a bit impressive.

4KB Random Read (QD3)

4KB Random Write (8GB LBA, QD3)

Shifting over to random performance, read performance once again looks excellent. Even reading 4KB at a time the drive sustains 75.9MB/sec, again easily surpassing any other drive. The one downside here is random write performance, which tops out at 73.4MB/sec, some distance away from our rMBP. I’d be curious to see how well the 512GB drive performs in comparison, but I have to imagine Apple has already filled out their NAND channels at 256GB.

In any case, we’ll be following this up with a deeper look at the MacBook’s SSD. Hopefully we’ll be able to find out more about the SSD controller’s manufacturer after a tear-down, and with a bit more work we can also run it through our other storage benchmark scenarios, looking at things such as performance consistency. So stay tuned.

The MacBook’s Retina Display: Pro Quality OS X Performance
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  • lilmoe - Tuesday, April 14, 2015 - link

    "I’m going to start where I left off in our introduction, which was the concept of the laptop/tablet crossover. The idea of laptops and tablets crossing over is no longer merely an idea, but now it is reality"

    Yea. Back here, we call those "Netbooks". But "crossover" sounds cooler.
    Reply
  • darwinosx - Tuesday, April 14, 2015 - link

    You don't know what a netbook is. They were cheap devices with low quality screens and poor build quality. Try reading the review you are commenting on. Reply
  • lilmoe - Tuesday, April 14, 2015 - link

    OK, so it's a better quality netbook. Got it :P Reply
  • vFunct - Tuesday, April 14, 2015 - link

    Sorta like how a laptop is a higher quality netbook.

    Or, how a computer is a higher-quality calculator.
    Reply
  • PEJUman - Tuesday, April 14, 2015 - link

    Maybe in 2012 laptop is higher quality netbook. I am starting to feel that Anandtech is getting too 'careful' with the OEMs. M9 is bad, call it that. this Macbook fits squarely in the netbook term from functionality standpoint, despite the price premium for the fit and finish. No need to redefine a new 'crossover' term just to keep Apple marketing managers happy.

    Right now, chromebook and other ultraportables (such as this one) with the relatively slow core M are the de-facto sucessor to netbook. Single usb port also a netbook typical compromise. It not convertible nor it has a touchscreen, so.. NETBOOK.

    Tech evolves, therefore performance expectation should evolve with it. the core M is barely faster than a 2012 intel i3-3217U on geekbench. It is the lowest performance tier of Intel big core family.

    Anandtech used to be unbiased, I think they finally started the slow descent towards 'marketing for OEM'. I understand where this is coming from, and I am willing to pay for anandtech subscription if that what it takes to restore the one place a techie can get an unbiased, deep dive into new techs.

    Purch should differentiate Tom's & Anand by using Tom's for their mainstream, 'marketing compatible portal' while turning Anand into a subscription based portal, with reviews selection based on customer votes, each one completely unbiased, purely technical, pull-no-punches style.
    Reply
  • ws3 - Tuesday, April 14, 2015 - link

    Something like the transformer book is a modern day netbook: atom processor, $300 price, questionable build quality --- all the traits of a netbook. Reply
  • BittenRottenApple - Wednesday, April 15, 2015 - link

    Yet another fine addition to the long list of "Terrible Products Apple Makes to Gouge Money out of People".

    The new MacBook is a testament to Apple's collapsing technical acumen. They eliminate all ports except for one outdated USB port? This craven stupidity should send the last adherents running. But running to what? Windows isn't even a viable option anymore, since it now is the most widespread commercial NSA gathering tool available, closely followed by Android, iOS and OS X.

    It's a sad day for people who need real computers. Jony Ive is a pompous, clueless hack who should be fired for introducing crippling regressions like this one.

    Look at this POS: One USB port, which will require an adapter to do anything. So if you're going to require an adapter anyway, why not make that one port a modern one: Thunderbolt. Thunderbolt can carry USB, video, Ethernet, external storage... ALL AT ONCE. And it can be daisy-chained, which is hugely important when the computer has ONLY ONE PORT. So WTF is Apple doing making its sole port USB?

    And again, are you kidding me? One tiny USB connector? Now every sorry user of this pos has to find a thunderbolt to USB C, a USB C to USB to HDMI, a USB to USB 3.0 period, a USB C to USB connector for apple’s time machine and also manage to don't short circuit all that with the AC/DC to USB C connectors, seriously ? Worth 200$ new pile of hairy connectors for the brand new gold macbook air, and that is called a revolution nowadays? No ********** way, the Dell XPS 13 is way superior, period.

    By the way, they're perpetrating USB Type C connectors. Thunderbolt is a much-needed step to a modern I/O standard. USB is an outdated, abused standard that was designed for keyboards, mice, and modems. It's not suitable for external storage, video, or anything else requiring bulk data transfer with minimal CPU overhead. USB C is a regression, a major step BACKWARD.

    $1599.99----Less than $550.00 worth of hardware = ~$1000 premium to use OS X instead of windows. (Honestly the most expensive component of this computer is probably the screen.)
    Anyone with real work to do will not even be able to buy this thing. My friend’s last Air was neat in that it was small and lasted all day, but it was so under-powered, it was frustrating. I can only imagine how limited this machine will be.

    Who cares about price, weight and size, when this product is crippled by a hopelessly defective design? You can't hook up a power adapter and external storage at the same time. You can't hook up an external display and external storage. Hell, you can't even plug in a thumb drive!

    This product is the most asinine piece of shit Apple has produced, and that includes the (thankfully) short-lived Shuffle that could only be controlled by a gimped Morse code.

    $700 less gets you the new Dell XPS 13 which will eat the Mac's lunch.

    If you need to do a lot of processor intensive work, than you would not even go near this thing. It would be useless to you. If you need to crunch spreadsheets or are heavy in corporate analysis, this computer would also be useless to you.

    This is the kind of computer that Apple sells a lot of. This computer is largely useless for anything other than email and facebook. It cannot store many files, it cannot process much information, and it has one external port. There is nothing wrong with using this computer for casual tasks, but it is CERTAINLY not a productivity machine.

    It is what it is. A status symbol/statement. Or some other statement. A statement that you just bought a $400 netbook with a $900 case so you can show off in front of your hipster friends.

    I hate to stick to Apple only facts here, but Apple said that the Air is 24% thicker than this new Macbook. That does NOT mean that the new Macbook is 24% thinner than the Air, it means that it is ~20% thinner than the Air. They clearly phrased it that way to make it sound more impressive and hence dupe the consumer, aka stupid isheep.

    So, it's an iPad plus with a keyboard and an over expensive dongle so you can do everything a Dell can do, at twice the price while looking posh.
    And here I thought technology was about function over form. I get it, functional art; art I can do things my phone does, but in a space that anyone can see me doing it, stylishly. Crippled and non standard in-house branded "business" software does great, can't do anything really artistic on it except maybe GarageBand or stock filter photo edits to my innumerable selfies, but it's got that partially eaten fruit on the back that screams "money I'm too stupid to keep or invest wisely."

    Take my money!
    I wouldn't hold my breath.

    This is apple's marketing strategy: mind-numbing markup on dirt-cheap, mediocre laptops. They throw together a cheap little laptop, pretty it up with silver or gold paint, and ride the wave of ignorance, outrageous markup, and marketing that they've been using as a business model for many, many years now. The only thing Apple has ever made that's less worthless than all the other crap their conspirators like Hon Hai Precision Industry Co., Ltd excrete all day and night by taking advantage of child labour are iOS and OS X which, besides being notoriously crippled and constrained walled gardens, aren’t even worth the hassle unless you also dumped thousands of dollars into other apple products.

    Many apple owners I’ve encountered never stop trying to belittle and demean others because they don’t have a Macbook or an iPhone and then try to act like their overpriced apple products are overall better when they are certainly not, by any standard.

    Luxury cars, while still worthless crash grabs, usually offer some quality and features that are actually somewhat superior to cheaper competing brands and models.
    Macbooks such as this start already expensive as hell with little performance to warrant such outrageous costs. Apple isn’t the luxury car of anything. It’s the luxury car DESIGN with a 4-cylinder under the hood and a tape-deck in the sound system, all with the price tag of "luxury". They sell laptops made cheap in china, using child labour and the same hardware you can find in SO many other laptops, slap their OS on it, put it in a thin case, and then markup the price by 300% to 600%. These are the facts. This laptop in question is nowhere NEAR worth that kind of money. I mean, laptops in general are overpriced, but apple has made their entire business model out of extreme markups backed by clever marketing with little actual technological superiority of any kind. Every single apple product on the market can be outperformed in every way by comparable products. Apple computers can be outperformed by computers that are FAR FAR cheaper while relying on older tech. The only thing that apple has that nobody else does is OSX and iOS, their operating systems. These are mediocre operating systems, but they are literally designed to be limited on anything it determines to be "non-apple hardware". Other operating systems can be installed on just about any computer you can slap together, whereas OSX is specifically and deliberately designed to be non-functional on ANYTHING that isn’t made by apple. It’s nothing but a cash-grab.

    Apple is indeed playing run-of-the-mill capitalism, they try to capitalize on the ignorance of the average consumer with marketing campaigns designed to make you assume you're getting your money's worth.

    There are millions of consumers who are on the fence, who are actually interested in buying something that's worth the money they spend. Those people deserve factual information and do not deserve to be exploited for their ignorance on the topic. So excuse me if I have a problem with it. College students especially, who don’t have a lot to spend in the first place, are being taken advantage of in every area of their life. Buying a computer should be one less area of exploitation. This is why I have a problem with apple and with many other companies and services that attempt to capitalize on ignorance.

    Years down the road when the batteries in this model are dead and you have to keep it plugged in just to use then you'll have no way to plug in a flash drive or an external hard drive. I don't care how sexy it looks: sometimes and more often than not less means a serious lack of functionality.

    We can only hope that consumers send this piece of diabolic garbage to oblivion, as they did the idiotic iPod Shuffle that could only be controlled with Morse code over a proprietary headphone wire.
    Reply
  • Notwist - Wednesday, April 15, 2015 - link

    You literally just typed a small novel spewing a bunch of claims without citing anything to support your arguments, or outright fabricating stuff. It's the absolute definition of a poorly written, complete waste of time. Please take your rants elsewhere, Anandtech readers, last I checked, enjoy discussing tech, not spouting conspiracy theories and raving like lunatics. Reply
  • superflex - Thursday, April 16, 2015 - link

    I thought it was quite good.
    You sound like a butthurt iFanboi
    Reply
  • star-affinity - Friday, April 24, 2015 - link

    I thought it was bad and not nuanced at all. Things aren't that black and white. Reality comer in many shades.

    People have the right to have an *informed* opinion. The long post above is unfortunately based mostly on ignorance.
    Reply

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