I have iMac mid 2011 2.7Ghz running yosemite. Three user accts, one admin, 2 other kids. I have a few external hard drives holding photos, movies, music. The one hard drive ( WD 2TB My Book Studio Edition II Quad Interface External Hard Drive) is the drive I am asking questions about. I currently have it connected via FW800 and it is the only drive using FW. This drive has a power switch but it still turns on all by itself when anyone logs onto the iMac. (it's not an "old school" rocker power switch.. its a newer type of button) When I use the iMac, I would like to have access to the drive... and allow the drive to power up, mount, spin and function. When the kids come home after school and power up the iMac, i do not want the said drive to power up, mount ..... I want it to remain off, dormant. is this a possibility?