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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darwinosx - Monday, June 24, 2013 - link
Another peson who didn't read the article and knows nothing about Macs.watersb - Monday, June 24, 2013 - link
Excellent review!If only it were available with RAM...
darwinosx - Monday, June 24, 2013 - link
If only you took tow seconds to find out you can order it with 8 GB of ram.appliance5000 - Friday, December 20, 2013 - link
It's available with 8gb ram - but here's the rub: If you have the 512gb ssd coupled with the fact that it's mounted on the pcie bus, your page ins and outs are about as fast as memory - or seemingly so. It's a very fast machine - I've tested it stitching multi gb panos and editing multi gb layered files in CS6 and it just rips.FrozenDarkness - Monday, June 24, 2013 - link
I think people get retina confused with higher resolution computers. Couple things, your windows computer? DPI up scaling sucks too much to truly run retina. Know that retina on a 13 MBP actually runs at a resolution of 1280x800 to be truly "retina" or else you're just up-scaling then down-scaling and burning your graphics card in the process. So in a sense, it's not truly higher resolution in terms of workspace, just in terms of beauty to behold. This also means a MBA retina would have to be a different, higher resolution panel, than the one used in the 13" MBP and at that point, what is the point of the MBP? I think you're more likely to see the MBP become more lik the MBA in size than vice versa.Also, panel lottery sucks, let's not act like apple is the only manufacturer who has a panel lottery or that samsung are only in "review" units.
A5 - Monday, June 24, 2013 - link
Windows 8.1 is supposed to fix the DPI scaling in Windows. Win8 is already significantly better than 7.Beyond that, sharper pixels even without an increased workspace is still a good thing. I think the rMBPs have a mode that does both, anyway.
JarJarThomas - Tuesday, June 25, 2013 - link
Windows 8.1 can't fix the dpi scaling in windows cause the problem is that most desktop applications can't scale well.Fixing dpi scaling with win8 would be similar to the solution apple does for non retine enabled grafics, internally upscale it.
But that would not work with the way the windows grafic stack works and the applications are dependent on this.
So scaling will ONLY be better for modern ui apps, not for desktop apps.
And therefore it will suck
akdj - Wednesday, June 26, 2013 - link
'Desktop applications can't scale well' because and ONLY because of the underlying OS. It's up to the operating systems architecture to provide third party scaling options/abilities. As we've seen with the rMBP....in less than a year, literally hundreds of apps....from small developers ala Pixelmator to the monsters...AKA, Adobe....have updated their 'code' for HiDPI displays. As has Apple with their software....and Windows with their native apps. Look at the Surface Pro for instance. Anything other than native Windows programming is a PITA. Windows 8.1 absolutely can help...regardless of how the graphic stack is set up....it's that low level coding that Windows needs to get creative with. Especially with dozens of OEMs, screen sizes and ratios....it will absolutely fall into Windows hands to provide decent scaling options and APIs for developers. High Rez monitors aren't going anywhere. 4k was all the rage at CES this year....and $7,000 Sony 4k TVs are already at Best Buys.OSx meanwhile has done an excellent job with pixel doubling trickery for text....while allowing developers the ability to natively use every pixel available 'in app' when drawing, editing video or stills....et al.
That said, and as a rMBP and 11" Air owner, I can honestly say the Air's resolution doesn't bug me in the least. It's a 2011 core i7 and I use it daily....right along side my 15" rMBP...which is the best computer I've ever purchased. Almost a full year with it and it still brings a smile to my face. I started my computer life @ 14 with an Apple IIe in '85. I remember being jealous when my buddy got the 'color' screen for his IIc...while I continued to slave away on a green monochrome screen. Lol....I suppose its where we come from, our ages....and therefore, appreciation for higher resolution vs decent resolution (11" Air) more than adequate and a helluva lot better than other choices on the market. Dunno
Bkord123 - Tuesday, June 25, 2013 - link
I do not claim to know a ton about computers, and I'll be honest, half of this review looks like it's written in Latin to me. However, regarding the comment that Windows 8 is better than 7, didn't I read several headlines that Windows 8 is more or less responsible for a massive decline in PC sales?TheinsanegamerN - Sunday, June 30, 2013 - link
the main reason pc sales are declining is a mix of a poor economy and computers lasting longer. machines reached the point of being fast enough for consumers five or six years ago. most consumers dont run out to get the newest thing in laptops, they wait until their current one breaks, which is more pronounced when jobs are not certain and raises are nonexistent. they were declining before windows 8 made it to market, though windows 8 isnt helping at all.