Do you ever turn off your external hard drive? I got mine (LaCie 1 TB, USB) always connected when I'm at my desk and the HDD is always powered, meaning I don't turn it off at the back (there is the power switch). The HDD goes into sleep mode whenever it's not doing anything, but still, is this bad for my ext. HDD to keep it always powered? Or should I turn it off when not using it?