Wednesday, 13 April 2016

MacBook Pro and USB - Interesting Quirkiness

I'm using a MacBook Pro: -


I've seen this a few times: -

034378.680514 SSP4@14700000: AppleUSB30XHCIPort::resetAndCreateDevice: failed to create device after (1) tries, disabling port
034414.624087 SSP4@14700000: AppleUSB30XHCIPort::resetAndCreateDevice: failed to create device after (1) tries, disabling port
034416.245827 SSP4@14700000: AppleUSB30XHCIPort::resetAndCreateDevice: failed to create device after (1) tries, disabling port
037923.490801 SSP1@14500000: AppleUSB30XHCIPort::resetAndCreateDevice: failed to create device after (1) tries, disabling port
037961.216945 SSP2@14600000: AppleUSB30XHCIPort::resetAndCreateDevice: failed to create device after (1) tries, disabling port
038140.039979 SSP2@14600000: AppleUSB30XHCIPort::resetAndCreateDevice: failed to create device after (1) tries, disabling port


when I insert a USB 2.0 or USB 3.0 hard drive.

I only started looking in the system log ( sudo dmesg ) when the USB drives failed to materialise in Finder or Disk Utility.

Previously I'd "solved" this by rebooting, which is a pain.

For the record, I also saw the same on a Mac Mini


This time around, I had a quick Google and found this: -


which said, in part: -

All Macs with USB3 ports are UASP capable and UAS in enabled by default. Since Mountain Lion 10.8 Apple has included kernel extensions (kext) for UAS. In System>Library>Extensions>IOUSBAttachedSCSI.kext (Apple wouldn't include the kext if Macs didn't support UASP)
So yes, Macs do, by default, I might add, use UASP when a UASP enabled device is attached using a USB3 cable. If a UAS device is not detected, then Macs revert to BOT. This has been true since at least the rMBP released in 2012. (Which is what I'm using right now)
...
On occasion, UAS will not be used due to USB hubs, USB2 devices being inserted into the ports (shared bus) and when the USB3 port gets stuck in BOT protocol. Always best to attach a USB3 UAS device first into the USB 3 port. If the Mac gets stuck on USB2 or BOT, removing all devices and a reboot normally clears it.

Taking this into account, I tested by plugging the USB drive into a USB 3.0 hub: -


This time around the drive just worked ….

… which is nice

Weird but nice :-)

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