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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smilingcrow - Monday, June 24, 2013 - link
Says the person complaining about other peoples' immature posts.darwinosx - Monday, June 24, 2013 - link
Most projectors use HDMI, VGA is long dead. You could have taken two seconds to Google VGA adapter for MacBook Air to find there are many options though. Putting a VGA port an an Air would be idiotic. Actually on any modern laptop.SirPerro - Monday, June 24, 2013 - link
VGA is dead already. LAN... Well, I haven't tried a WiFi connection that comes even close to wired. And that's not going to happen in the near future.Apple doesn't look to the future. Apple looks to the wallet. And certainly charging some serious money for cable adaptors which everybody else includes for free is a very good move towards their target.
And yes, if they removed RJ-45 because it was too thick, they could've used a 50c adaptor to a phisical smaller interface. But that wouldn't be so profitable.
Kevin G - Monday, June 24, 2013 - link
There plenty of space to put in an RJ-45 jack into the Macbook Airs if Apple didn't care about ascetics: in the bezel of the LCD display. Part of the Cat5 cable would go through the the RJ-45 hole in the display. I'd only work with the screen open but for a wired connection it wouldn't be much of an issue I believe. The problem is that this is a pretty fugly solution.darwinosx - Monday, June 24, 2013 - link
Ah so you are a laptop engineer..no...an adapter is fine for those who need it.Kevin G - Monday, June 24, 2013 - link
An adapter is easily lost.... the display only gets lost with the rest of the computer.AirieFenix - Thursday, June 27, 2013 - link
Putting a RJ45 connector on the bezel of the screen... yeah, I prefer to not comment.Spoony - Monday, June 24, 2013 - link
I work for a large corporation too. I know that projectors are all VGA, and everybody uses PowerPoint to show awful ugly presentations with slides just repeating what they say with zero value-add. Anything we can do to exit this model has my full support, and not shipping ANY laptop with VGA would be a great start.Don't make excuses for lame prehistoric corporate IT, demand better.
lilo777 - Monday, June 24, 2013 - link
Yeah. Marketing spin in this review was stronger than usual. Here are some examples."To hit an aggressive schedule, you have to mitigate risk." Really? Since when Apple's schedule has become aggressive? Launching 5 products per year which in most cases have very little changes. It's not like the previous version of MBA was released three months ago.
"We’re talking about TN panels (admittedly higher quality than most) and traditional pixel densities. Compared to the Retina Displays deployed across the rest of Apple’s product lines, these panels just aren’t as good. Compared to what you typically find elsewhere, they’re still among the best." "Typically find elsewhere"? Are they trying to compare MBA with $400 laptops? If you look at the same price range (Sony Vaio Pro, Samsung 9 etc.) you will find much better displays than what MBA has. It looks like being an Apple customer Anand has developed an attachment to the brand that interferes with the quality of his reviews.
darwinosx - Monday, June 24, 2013 - link
Everything you said is wrong and ignorant but the dumbest is accusing Anandtech of bias.