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.
Facebook
Twitter
RSS
233 Comments
View All Comments
appliance5000 - Friday, December 20, 2013 - link
One word - tablets.mikeztm - Monday, June 24, 2013 - link
Could that PCIe ssd works with Filevault2 without performance down?My 2011 MBA's SSD became much slower after enabling Filevault2.
|-8-| - Monday, June 24, 2013 - link
>Five years after its introduction, the MacBook Air really has>grown into a very polished, mature platform. The 2013
>model is really the epitome of what Apple set out to
>build back in 2008, we just finally have the right hardware
>available to realize the vision. Nearly every component has
>been perfectly selected.
For a ultramobile working horse, there are still some substantial shortcomings: It's still a glossy display tying your work place to indoor use or cloudy weather. There is still no LAN, no VGA - this makes many headaches in business everyday life.
Maybe the author better leaves the marketing to Apple and concentrates on listing the Pros AND Cons of the product. It's a fine notebook, but definitely not perfect. ;)
weiran - Monday, June 24, 2013 - link
You forget not everyone works in a corporation and has your requirements, especially considering this is a consumer device first and foremost. Apple looks to the future, which may mean minor pain in the short-term (having to use adapters for LAN and VGA), but realistically do you think in 2-3 years either of those will exist on any consumer laptop?|-8-| - Monday, June 24, 2013 - link
It's not about having these or that requirements. The author is praising something to the skies, that has obvious short comings. (Every product has that.) What would be more 'neutral' verbalised: The components are perfectly selected. [...]. There are a few compromises, so the screen has good contrast, but isn't really usable outside, for example in a park. Further missing legacy ports force to carry adapters for using old legacy infrastructure like LAN networks or common LCD projectors.It's about writing a review - I don't want to read someones marketing arguments.
And by the way: Yes, VGA and LAN will be important in the future - most LCD projectors still have VGA and in contrast to HDMI or Displayport it really works reliable. I was at a conference a month ago - VGA saved me as Displayport wasn't working at all.
LAN is without alternative to share and synchronise big amounts of data.
Grennum - Monday, June 24, 2013 - link
VGA is certainly dying. By the end of the year all of the projects in our boardrooms will be replaced with Smart Screens, which you connect to via Wi-Fi. We have wired HDMI as a back-up works perfectly.Wired LAN is not dying by why would you ever have large amounts of data on your ultra portable laptop? That is just be irresponsible. If you are working with large data sets best to do it on a remote system where you have the performance, and reliability.
This laptop would perfectly meet the needs for many of our business users, maybe not engineering, but then engineering wouldn't be looking at an ultraportable (remote engineering desktops notwithstanding)
|-8-| - Monday, June 24, 2013 - link
Maybe I should switch to your company. ;) There are some new projectors here having HDMI (sadly no Displayport). But most projectors are quite old (still working), these are connected via VGA. There is some time left, till the last old projectors die.Honestly I don't see a bonus in digital alternatives. THE standard is still missing, as most notebooks have either HDMI or Displayport.
WLAN seems to have high signal latency between two computers. If you syncronise two big collections of many many subfolders and many small files in there, you notice a huge difference even between 100 MBit/s LAN and 300 MBit/s WLAN. I use WLAN for backups, but speed sucks.
Another problem is security of data in the private sector, these security guys don't like WLAN.
A5 - Monday, June 24, 2013 - link
Then maybe don't work in a park? I don't know of any laptop with a bright enough screen and good enough battery life to actually work outdoors.|-8-| - Monday, June 24, 2013 - link
Well, the Samsung Series 9 900X3C-A04DE or the Lenovo x220/x230 are two, that can be used outdoors. There should be more, some Zenbooks have also matte screens.darwinosx - Monday, June 24, 2013 - link
Well Samsung makes cheap junk that doesn't work and has no support.