USB3 by Apple

[AurelMax]

Hi everyone

I'm not sure where I should post this as it concerns both MBP and MBA 2012... But like many other people, I've been having troubles with a USB3 external hard drive and my new MBA

EDIT : allright, as for the hard drive speed question, the cables seem to be the problem.
And as below, it appears that the FAQ is just poorly written
thanks to everyone

I looked up what Apple says : http://support.apple.com/kb/HT5172?viewlocale=en_US&locale=en_US


Pay attention to Q7 & 8 :


How do I get the best performance from the USB 3 ports?
The first device you plug in will configure the port, so always connect USB 3 capable hubs or devices first.

What happens if I plug in a USB 2 device into the USB 3 port first?
If you plug in a USB 2 hub first, all devices connected or "daisy-chained" to that hub will operate up to the maximum transfer rate of USB 2 speed (480 Mbps).



First time I read this, I think everybody should know... I think some people are gonna have to clean install ML again

 

[LostSoul80]

I doubt you have to clean install ML. That document is not precise as it doesn't specify the context. I suppose that "first time" is referred to a single session. Restarting your Mac and connecting the USB 3 device should work. Have you tried it yet?

 

[AurelMax]

Thanks for replying


Well actually yes I did...

VERY first thing I plugged in the right usb port? iPhone... so that's USB2 I guess

In the left port? USB3 Hard-drive... it has not worked, worked, not worked, not worked...


Now, the hard drive can be read in the right usb port, which has been occupied by the iPhone till then... iPhone works great in both ports.


But in System Information, I'm told that both ports (or hubs? sorry if I use wrong terminology) are High-speed USB, thus limited to 480mb/s

 

[Serelus]

How is this even possible, why would they configure the system so it keeps whatever configuration is plugged in first. That seems very sloppy regardless of the context...

 

[Aksta]

have u tried running a speed test on the hard drive to see if there isnt a problem with the system information. i have tried to replicate your problem with an iPhone and a usb 3 hard drive but cant do so.

 

[Ifti]

How do I get the best performance from the USB 3 ports?
The first device you plug in will configure the port, so always connect USB 3 capable hubs or devices first.

What happens if I plug in a USB 2 device into the USB 3 port first?
If you plug in a USB 2 hub first, all devices connected or "daisy-chained" to that hub will operate up to the maximum transfer rate of USB 2 speed (480 Mbps).

The way I took the above is that if you daisy chain devices with a USB2 device plugged into the laptop, then the bottleneck is the device connected to the laptop, hence all the others in the chain will be limited to the bottleneck.
Whatever is in the daisy chain, the port on the laptop will be configured to the speed of the device directly connected to it.
Makes complete sense to me.

You cannot permanently configure a port by plugging in a certain device. Once the device is unplugged from the laptop, the port will be switched off until the next device is connected, and it will configure itself for that device.

So, if you connect a USB2 device, the port on the laptop wil be configured for USB2 speeds, no matter what else is daisy chained to it.
If you the remove the above and connect a USB3 device, the port reconfigures to the correct speed.
You cannot connect a USB2 device to the laptop and then daisy chain a USB3 device to it, and expect to achieve USB3 speeds, since the port will have configured for USB2.

This certainly works for me.
I've been using USB2 devices, such as my iPhone and iPad first. I then purchased a USB3 external drive, and connected this, performed a disk speed test, and can confirm I get USB3 speeds.

 

[LostSoul80]

The way I took the above is that if you daisy chain devices with a USB2 device plugged into the laptop, then the bottleneck is the device connected to the laptop, hence all the others in the chain will be limited to the bottleneck.
Whatever is in the daisy chain, the port on the laptop will be configured to the speed of the device directly connected to it.

That addresses the second part, however the strange answer is the following

How do I get the best performance from the USB 3 ports?
The first device you plug in will configure the port, so always connect USB 3 capable hubs or devices first.

It doesn't mention directly daisy chains, but specifically "devices" (and hubs, of course).
So, either that Q&A is very badly written, or that's plain weird.

 

[sweetbrat]

The way I took the above is that if you daisy chain devices with a USB2 device plugged into the laptop, then the bottleneck is the device connected to the laptop, hence all the others in the chain will be limited to the bottleneck.
Whatever is in the daisy chain, the port on the laptop will be configured to the speed of the device directly connected to it.
Makes complete sense to me.

You cannot permanently configure a port by plugging in a certain device. Once the device is unplugged from the laptop, the port will be switched off until the next device is connected, and it will configure itself for that device.

So, if you connect a USB2 device, the port on the laptop wil be configured for USB2 speeds, no matter what else is daisy chained to it.
If you the remove the above and connect a USB3 device, the port reconfigures to the correct speed.
You cannot connect a USB2 device to the laptop and then daisy chain a USB3 device to it, and expect to achieve USB3 speeds, since the port will have configured for USB2.

This certainly works for me.
I've been using USB2 devices, such as my iPhone and iPad first. I then purchased a USB3 external drive, and connected this, performed a disk speed test, and can confirm I get USB3 speeds.

I read it the same way you did. It's not a permanent configuration. If you're going to daisy chain devices, put the fastest one first, because that's the one the port speed is configuring to. But each time you completely disconnect devices and plug them in again, it reconfigures to the speed of that device. It's really not a big deal, and would absolutely not mean you need to reinstall ML.

 

[dusk007]

I think you think too complicated.
That FAQ is written for complete idiots and from that perspective you need to read it.

First device means the one nearest to the actual port, meaning actually in the notebooks port. Devices is confusing but probably is supposed to include docks, extension cables and such.
They only mean to explain to those that have absolutely no clue that if you plug in some old USB 2.0 device (like a dock) it doesn't matter if the attached external HDD is USB 5.0, it will stay at 2.0.
Everybody with some clue would say, well sure how else could it work but computer illiterates don't make those connections and for those such FAQs are often written.

I agree though it is poorly written.

USB 3.0 works just like every other p&p device. Speed negotiation happens when you connect it. Sessions, restarts are moot.

I am very sure my interpretation is the wright one just look at the headings.

The first device you plug in will configure the port, so always connect USB 3 capable hubs or devices first.
What happens if I plug in a USB 2 device into the USB 3 port first?

The following heading/questions and its explanation who what they actually meant in the first answer even if they could have been more specific or phrased it better. Since using a USB 3 hub with a usb 2 ext. HDD also only results in USB 3 speeds they could have just said. Any chain will always only be as slow as the slowest member.

 

[AurelMax]

ok i'll try a speed test, any software recommended?

 

[KevinC867]

I agree with what others have said regarding the intent of that FAQ answer (the port is configured for USB 2/USB 3 according to the device which is directly connected to it).

However, I have also experienced a problem when I connected a USB 3 hub directly to the port on my rMBP and System Information reported that the port was still configured as a USB 2.0 port. In my case, the problem seems to have gone away after I rebooted my system, but I wouldn't be too surprised to see the problem return some day. I think Apple needs to clean up their USB software a bit. I think this FAQ shows that they know that things aren't quite right.

 

[latestmonkey]

the replies here make more sense than the FAQ.

I am however one of those people that just couldn't get my new MBP 2012 to even recognize an external 3.0 drive (specifically seagate).

Like most people I just gave up and hope for the best when I have to get a new drive.

 

[AurelMax]

ok I tried with two different WD hard drive, both USB3


tests are not finished so I'm not sure these are 100% exacts, but one W/R at 65mb/s , and the other one at 35mb/s !!


The fastest of these two I have just formated ...


Edit : so is the problem from the WD hard drive? I'd need to try with another device

 

[carestudio]

Thanks for replying


Well actually yes I did...

VERY first thing I plugged in the right usb port? iPhone... so that's USB2 I guess

In the left port? USB3 Hard-drive... it has not worked, worked, not worked, not worked...


Now, the hard drive can be read in the right usb port, which has been occupied by the iPhone till then... iPhone works great in both ports.


But in System Information, I'm told that both ports (or hubs? sorry if I use wrong terminology) are High-speed USB, thus limited to 480mb/s

What WD drives? models?
for what it's worth I am using CalDigit VR2 RAID (eSATA, USB3 and FireWire), the speed can reach around 200MB/s through USB3 port on rMBP.

 

[geoffreak]

Edit : so is the problem from the WD hard drive? I'd need to try with another device

Yes, these are normal maximum speeds for a HDD. You would need something faster to take advantage of the full USB 3 connection.