Can I boot from USB 3.0?
I used Macs a long time ago and I remember that you used to be able to boot them from external FireWire drives. After a spell in Windows land, I am back with a new MacBook Air and I’m assuming that this will boot from Thunderbolt. But will it also boot from a USB 3.0 drive? They are so much cheaper… Len Pritchard Possibly, but it isn’t guaranteed. To boot from an external drive, the Mac’s firmware must recognise the drive. In the days before Intel Macs, you could only boot from FireWire drives but since 2006 we have been able to boot from USB 2.0 external disks (and if you are patient USB 1.1 as well). Since the end of 2012, Macs have had the hardware for USB 3.0 support, but hardware support is only half the battle; you need operating system drivers as well. When the Mac starts up, the OS obviously hasn’t loaded yet (that’s what the boot process is trying to do) so the Mac is reliant on the firmware to interface with the USB controller, and the firmware drivers are much less comprehensive. Some USB 3.0 drives will work and others just won’t.
Seagate drives seem particularly troublesome, whereas Toshiba and Hitachi have a higher success rate. There doesn’t seem to be an easy way of telling in advance whether it will boot on a Mac, so make sure that you mention that this is what you want to do when you order; then you can return the drive if it doesn’t work.
You can boot from all external USB 2.0 drives, and some USB 3.0 drives as well.