I'm running Ubuntu 12.04 on my Laptop with two hard disks. The primary one is a SSD, whereas the second one is a spinning hard disk. Most of the time I don't need the second hard disk, I just use it for some larger files like movies etc.. Hence I send it to sleep with 'hdparm -Y /dev/sdb'.
However after resuming from suspend the hard disk is switched on again, which is quite annoying... Does anyone know a solution to avoid waking up the second hd?