When Mac goes to sleep mode (i.e, when we close the lid of the laptop, or power saving kicks in, etc.) it saves a hibernate file (/var/vm/sleepimage) first, and then goes to standy mode (thus the computer is on, it just stops running all programs and puts itself into a low powered mode). If you want your mac always to go to hibernate mode then execute the below commands with sudo privileges sudo pmset -a hibernatemode 1 (This effects when your mac is in all modes such as battery and UPS and AC) sudo pmset -b hibernatemode 1 (This effects only when your mac is on battery mode) Thats it! Now put the machine to sleep or just close the lid of your mac to put your mac directly to hibenate. If you want to reset back to default settings use following commands For Portable Macs( mac book etc) sudo pmset -a hibernatemode 3 ...