I want to be able to boot from an external drive as a fallback in case 10.7 update does not work out for my mac book pro. Not all external drives can be booted from according to Carbon Copy Cloner docs. I bought an external drive than realized I didn't know if I could boot from it. So, I cancelled the order. My mac book pro has firewire and thunderbolt ports. I presume it supports usb 2.0 and usb 3.0 I think firewire is going away eventually (?) What FAST and good external drives can I boot Mac OS X 10.7 from?