My book studio, never shut

Hi i have a mybook studio

http://support.wdc.com/product/download.asp?groupid=113&lang=en

connected by firewire at my iMac, but when i shut down the mac the disk never really shut down it always the fron light that goes up and down…

is it in a kind of standy i guess… but i’m not shur that the disk is off and not running

is that not very good for the disk?

how much power does it consume?

i ask because my other usb 2 disk seems to really shut after mac shut down

So funnny, I am thinking on getting a My Book 2tb to use with my WD TV Live Plus, but I was afraid that once you shut down the WD TV Live plus, My book HD will ramain on…like yours aparentely.  Aint all drives to shut down when no power from the USB cable?