Software Slowing Some Wi-Fi File Transfers on New MacBook Air

AirportextremeNetworking code in OS X Mountain Lion is slowing down file transfers over the Apple Filing Protocol (AFP) and Microsoft's Server Message Block (SMB), according to examinations done by both Ars Technica and AnandTech.

The issue affects the new MacBook Air models that come equipped with the 802.11ac Wi-Fi technology. The new MacBook Air and Apple's new AirPort Extreme base station are the first Apple products to use the new Wi-Fi technology.

Anandtech discovered that the TCP window size for file transfers in OS X was too small to reach the potential throughput on many file transfers, slowing data transfers from a potential 533Mbps down to 170Mbps.
The bad news is that in its shipping configuration, the new MacBook Air is capable of some amazing transfer rates over 802.11ac but you won’t see them when copying files between Macs or PCs. The good news is the issue seems entirely confined to software. I’ve already passed along my findings to Apple. If I had to guess, I would expect that we’ll see a software update addressing this.
Ars Technica confirmed AnandTech's findings, and went a bit further. The site discovered that when running Windows 8 in Boot Camp, the new MacBook Air saw file transfer speeds significantly higher than under a comparable setup in OS X Mountain Lion.
Some variation between the two operating systems is to be expected. They're very different under the hood, after all, and Microsoft's strong commitment to the enterprise (and the file servers therein) makes it unsurprising that Windows' file transfer speeds are generally a bit faster than OS X's. However, the discrepancy between the Windows 802.11ac speeds and OS X speeds is too large to be explained away by networking optimizations alone. Windows is, at best, about nine percent faster over Gigabit Ethernet and 30 percent faster over 802.11n, but it's 218 percent faster over 802.11ac.
Ars' OS X wireless setup saw transfer speeds of 21.71MB/s on SMB, and 47.26MB/s on a comparable Windows 8 setup under Boot Camp.

The issues also exist under the developer beta of OS X Mavericks, but both sites expect Apple to release a software fix for OS X that will solve the file transfer issues.

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20 months ago
some people are feeling this:
Rating: 10 Votes
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20 months ago

One would still think these issues should be more uncommon on Macs than they are since ”Apple makes both the hardware and the software”, no?


Haha the delusion of integration! It took a third party for Apple to do their testing and analysis for them after the product release. The Windows part gotta hurt the fanboys real bad :)
Rating: 6 Votes
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20 months ago

Not a big surprise. New hardware often has driver/software problems. No need to return new MacBook Airs. They will be fixed in a software update ;)


One would still think these issues should be more uncommon on Macs than they are since ”Apple makes both the hardware and the software”, no?
Rating: 4 Votes
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20 months ago

Haha the delusion of integration! It took a third party for Apple to do their testing and analysis for them after the product release.


Isnt that how apple do all the testing,

Apples process is something like this

step one, J.Ive design a case nothing with a reasonable performance can fit into.

Step Two, the hardware engineers go out and shoehorn whatever they can find that can kind of fit into that case.

Step Three, Apples marketing team has to spin the reason you can get a PC for a tenth the price with 4x the power almost solely on the J.Ive designed case and a load of specs that don't work yet and might be patched in later.

Step four, build a giant ring shaped building to put all the money in the middle of and swim about like Scrooge McDuck.

Now im not an apple hater, i love the OS, i just wish they would u-turn from this sealed unit lockdown, all our products are disposable, kick they are on , when its easier to replace the Harddisk in my PS3 when it fails than my iMac, something is seriously out of whack.
Rating: 4 Votes
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20 months ago
Not a big surprise. New hardware often has driver/software problems. No need to return new MacBook Airs. They will be fixed in a software update ;)
Rating: 3 Votes
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20 months ago
People must be holding it wrong :D.
Rating: 3 Votes
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20 months ago
In other words, a typical 1st revision Apple product.
Rating: 3 Votes
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20 months ago

Windows is, at best, about nine percent faster over Gigabit Ethernet and 30 percent faster over 802.11n, ...


Wow. I do a lot of Mac-to-Mac, Mac-to-Windows, and Windows-to-Windows transfers. Mac-to-anything transfered always seemed slower to me but I always thought I was imagining it. Am feeling disappointed now with the Mac's performance here. 30% over 802.11n is a large difference.
Rating: 1 Votes
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20 months ago
Nightarchaon, you forgot to add:

Step Five - PC manufacturers copy J.Ive design because that is the only way they can secure a premium price and make money on the device (witness products like HP's iMac and MacBook family clones).

;)
Rating: 1 Votes
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20 months ago

One would still think these issues should be more uncommon on Macs than they are since ”Apple makes both the hardware and the software”, no?


Haha the delusion of integration! It took a third party for Apple to do their testing and analysis for them after the product release. The Windows part gotta hurt the fanboys real bad :)


Integration doesn't mean there wouldn't be bugs. This is a software issue that can be fixed in a future update. It only affects SMB/AFP. The rest works fine.

For all we know, it's already been taken care of in Mavericks.


It hasn't been fixed in Mavericks according to Anand.

"Windows is, at best, about nine percent faster over Gigabit Ethernet and 30 percent faster over 802.11n, but it's 218 percent faster over 802.11ac."

Unacceptable for any protocol. Apple needs to correct this. There is no reason that a Unix based OS should be slower than Winblows in file transfer speeds.


It's just a bug in the TCP window sizing system for both AFP/SMB stacks. It's not resized to 256KB properly. Once they fix the bug, it'll just be normal fast.
Rating: 1 Votes
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