My LaCie “Big Disk Extreme with Triple Interface 500GB” (FireWire 400, FireWire 800 and USB 2.0) has recently started spinning down of its own accord. It will just suddenly spin down without prompting. Obviously, this is a bit of a problem.
From a bit of internet research, it seems that this is actually a problem with the power supply of these units, rather than with the drive itself. One email to LaCie technical support via their online support form later, and they’ve promised to send a replacement power supply, even though I’m outside my year’s support time.
Update: Received two (free) power supplies from LaCie. Tried one of them, and the involuntary spin-downs are gone. Hurrah!