The 2013 MacBook Air Review (13-inch)
by Anand Lal Shimpi on June 24, 2013 12:01 AM ESTA Custom Form Factor PCIe SSD
In the old days, increasing maximum bandwidth supported by your PATA/SATA interface was always ceremonial at first. Hard drives were rarely quick enough to need more than they were given to begin with, and only after generations of platter density increases would you see transfer rate barriers broken. Then came SSDs.
Not only do solid state drives offer amazingly low access latency, but you can hit amazingly high bandwidth figures by striping accesses across multiple NAND Flash die. A 256GB SSD can be made up of 32 independent NAND die, clustered into 8 discrete packages. A good controller will be able to have reads/writes in flight to over half of those die in parallel. The result is a setup that can quickly exceed the maximum bandwidth that SATA can offer. Today that number is roughly 500MB/s for 6Gbps SATA, which even value consumer SSDs are able to hit without trying too hard. Rather than wait for another rev of the SATA spec, SSD controller makers started eyeing native PCIe based controllers as an alternative.
You can view a traditional SSD controller as having two sides: one that talks to the array of NAND flash, and one that talks to the host system’s SATA controller. The SATA side has been limiting max sequential transfers for a while now at roughly 550MB/s. The SATA interface will talk to the host’s SATA interface, which inevitably sits on a PCIe bus. You can remove the middle man by sticking a native PCIe controller on the SSD controller. With SATA out of the way, you can now easily scale bandwidth by simply adding PCIe lanes. The first generation of consumer PCIe SSDs will use PCIe 2.0, since that’s what’s abundant/inexpensive and power efficient on modern platforms. Each PCIe lane is good for 500MB/s, bidirectional (1GB/s total). Apple’s implementation uses two PCIe 2.0 lanes, for a total of 1GB/s of bandwidth in each direction (2GB/s aggregate).
The move to a PCIe 2.0 x2 interface completely eliminates the host side bottleneck. As I pointed out in my initial look at the new MacBook Air, my review sample’s 256GB SSD had no problems delivering almost 800MB/s in peak sequential reads/writes. Do keep in mind that you’ll likely see slower results on the 128GB drive.
Users have spotted both Samsung and SanDisk based PCIe SSDs in the 2013 MacBook Airs. Thankfully Apple doesn’t occlude the controller maker too much in its drive names. An SM prefix denotes Samsung:
My review sample featured a Samsung controller. There’s very little I know about the new Samsung controller, other than it is a native PCIe solution that still leverages AHCI (this isn't NVMe). Within days of Apple launching the new MBAs, Samsung announced its first consumer PCIe SSD controller: the XP941. I can only assume the XP941 is at least somewhat related to what’s in the new MBA.
The Samsung controller is paired with a 512MB DDR3 DRAM and 8 Samsung 10nm-class (10nm - 20nm process node) MLC NAND devices.
New PCIe SSD (top) vs. 2012 MBA SATA SSD (bottom) - Courtesy iFixit
Despite moving to PCIe, Apple continues to use its own proprietary form factor and interface for the SSD. This isn’t an M.2 drive. The M.2 spec wasn’t far enough along in time for Apple to use it this generation unfortunately. The overall drive is smaller than the previous design, partially enabled by Samsung’s smaller NAND packages.
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vol7ron - Wednesday, June 26, 2013 - link
I'm sorry, have you ever owned an MBA? You don't want to be doing any heavy development on this device, it will get hot fast.This device should be the Traveler's Laptop: good enough to carry with you, more productive than an iPad, full keyboard, longer battery life than a regular laptop, lighter weight, and a few ports to maybe support what you need. It would be perfect for a plane or train, maybe to lounge by the pool, but should not be considered as a desktop or MBP replacement.
The shame of it is that it's so portable, that it leaves you wanting to do more with it. It almost has done it's job too well. In that regard, you are right, it is lacking the things that would put it over the edge, that would make it a replacement of the desktop/MBP, which again it's not. But be conscious that [I think] this has no fans, and from when I used it, got hot really fast -- horrible for any extreme development, or even long-term gaming.
darwinosx - Monday, July 8, 2013 - link
Hah! Lots of developers use Airs without issue.cscordo - Thursday, August 8, 2013 - link
What a ridiculous comment from someone who clearly doesn't develop software.I'm still on a 13" MBA from two gens ago and run multiple IDE's and SQL Server 2010, and it doesn't skip a beat.
What type of "heavy" software development do you perform that it can't handle? I'd be very interested to know.
josef195 - Tuesday, August 20, 2013 - link
So, you're saying the Macbook Air isn't for pro users? I must say, if only they had some Macbook for professional users; they could even call it a Macbook Pro.Calista - Thursday, June 27, 2013 - link
I agree with your ideas of adding the option of 16 GB of RAM and 4G support. Virtualization is growing all the time, the memory usage can grow very quickly if starting to run a few VM in parallel. And not having the option of 4G in this day and age is just embarrassing. For a machine *built* to be used on the go, with every component (battery life, weight, size) adopted to this task not adding 3G/4G just doesn't make sense.Dave DeCo - Saturday, June 29, 2013 - link
I have never given much thought to the 4G thing. But now that it's brought up I too wonder why the MBA doesn't offer it. My incredibly portable iPad has it. iPhone too of course. Why not the wafer thin MacBook Air? Oh Apple. Always dangling that carrot on the longest stick possible while telling us we don't need carrots. If that last line makes sense to anyone please tell me. Because I don't know what the Helsinki I just said.australianm8 - Saturday, July 6, 2013 - link
A few considerations for everyone fussing about 4g support.1. Apple likes to keep a simple product line
2. Look at a teardown, not much room in there for much more to add. (already pushing it's thermal limits)
3. There are a plethora of cell carriers that offer 4g USB sticks
darwinosx - Monday, July 8, 2013 - link
That was a childish and ignorant display of petulance. Obviously a particularly immature teenager.jaycee1970 - Saturday, August 24, 2013 - link
"Dump your apple stock now, it will bounce back"Wow, that's fantastic financial advice, genius. I'll definitely sell something that will go up in value. The rest of your post was just as intelligent. Thank you.
othernet - Monday, November 4, 2013 - link
Uhm... there are hybrid notebook/tablets out there. Did you buy one? I don't know of anyone that did.Apple sells Retina 4, 10, 13 and 15 inch products. Soon, an 8 inch product too. You must have missed the keynotes.
Wireless charging? Wait, do you still need to plug the wireless charger somewhere to make it work? When it doesn't have to sign me up!