Have a mac pro tower with Lion. I have had two G-Tech drives fail. On one of them, the power supply failed, not the disc. I just bought a new G-Tech drive 2tb. Use it on Time Machine (have another internal back up drive using Carbon Copy Cloner and a portable LaCie drive, also using CCC, which I keep offsite). I have had problems with the new 2tb G-Tech. Time Machine was showing error messages. The drive wouldn't erase my data. I called G-Tech. The tech worked me through setting up the unit, and it worked fine. He told me that it was their newest version, and they had sent them out from the factory incorrectly configured. Worked well for a week....got failed back up messages again today. I ejected (had to force eject the drive), and rebooted. It's working again. I want reliable external drives, since I use them to protect my data. What is the most reliable MAC compatible drive out there?