I've bought a SOC thing (ODROID XU3) to mess about with and eventually make into a little media player to keep connected to the TV for emulators, movies and music. I was going to add an external HDD to it to store all the media on.
I'll be running Retroarch and XBMC and whatever for music using Android as the OS (possibly Linux)

My question is if I was to get a 2tb Western Digital My Passport Ultra and left it connected to the device would it always be able to access the HDD or would it go into a sleep mode?
I'm just asking as I would scrape all the game covers, album covers and game covers onto the HDD too so if I switched to the device I'd want all those to display straight away.