Macbook Air usb3 not working!

I have a USB 3 thumb drive - Kingston Digital Data Traveler Ultimate 3.0 Generation 2 - which works just fine on my MacBook Air mid-2012 13" 8GB machine. The USB ports on the MacBook Air support both USB 2 and USB 3, but I can tell from the transfer speed to the thumb drive that it's working as a USB 3.

I was wondering about USB 2 drives, i don't have any USB 3 devices.

I've used several USB 2 thumb drives as well as the Kingston USB 3 drive I mentioned on my mid-2012 MacBook Air, all with no problem.

I have just bought a MBA and a Lexar 64Gb USB3.....and the MBA doesn't recognise the drive. It is fine with usb2 devices. Very annoying as I am away and want to save a load of photos on to the stick.

I have the exact same issue!

I have a 2012 MBA and a Toshiba Canvio USB 3.0 external drive that's partitioned for Time Machine and misc. files.

- The drive gets mounted most of the time. But sometimes it either does not mount, or the icons show up but the drives are inaccessible.

- The dive often disappears on the Mac, then Mac complians to me for not ejecting it properly.

I would love to see a solution soon!

Same issue here. My external drive keeps randomly disconnecting.

Actually it seems that the problem is related to external driver power consumption. The MBA just doesn't deliver enough current to power the drive. However the ports on 2012 MBA are able to provide some extra power (as verified by connecting the iPad to the USB port). When I connect the external drive to my MBA I'm getting the following values in System Information:

Current Available (mA): 900

Current Required (mA): 224

Obviously that's not enough to power the external drive (WD passport 1 TB USB 3.0). However when connecting the iPad I'm getting:

Current Available (mA): 500

Current Required (mA): 500

Extra Operating Current (mA): 1600

That's exactly 2.1 A of current - sufficient to power any external device. If I only knew how to force the port to supply more current to the external drive, my problem would be solved. Anyone has any idea how to fiddle with the power values on the USB bus ?

Just to double check ... are you all running current software? This article discusses the fact that a software update came out last month addressing this issue: http://support.apple.com/kb/HT5384

All the updates installed - running the latest version of Mountain Lion. I was hoping that "...and it improves compatibility with some USB devices." was related to my external drive issues, but apparently not.

Strangely enough I had the same problem with a Toshiba drive BUT if I plug it into a USB2 hub my MBA recognizes the drive... Directly,... no dice.

I have installed all updates and now run Mountain Lion, but it still does not work. :))

I used to have the same problem: the WD Passport would mount on all other computers, except on the new MBA. As discussed already, it's probably caused by a lower power throughput. I then tried replacing the original USB3 cable with another (longer) one which I use for a large external HDD drive. It did the trick - it now works without problems.

My assumption is that the connection to the drive might not be that "tight" (I've had connection issues with my MBP and USB 2 WD Passport drives in the past as well). As soon as the power goes beneath a certain threshold, the bad connection isn't able to overcome its resistance. The better connection of another cable/plug decreases that resistance, therefore solving the problem.

Give it a try.

Thanks for your advice. I tried it with my USB 3.0 hub cable - the MBA wouldn't detect the drive at all. Will try tomorrow with a premium Lindy USB cable, maybe that will work. Strangely enough the WD Passport works through the USB 3.0 hub without issues using the WD provided cable.

so has anyone seen an improvement with 10.8.1? better USB 3 support? external HDs staying connected??? please post any results/observations here to share your experiences and insights re 10.8.1!!

confirming NO improvement in USB 3 support for external USB 3 HDD. HDD spins up/spins down, spins up, spins down ad nauseum. Connection and use 100% through USB2 hub, but useless when directly plugged into USB 3 port on MacBook Air (mid-2012)

a shame as 10.8.1 didn't fix the external HDMI video output issue either

oh well, perhaps 10.8.2 might fix it!