Why does my early 2011 MBP hibernate instead of sleep? If and only if my MBP is plugged in to both AC and an external DVI monitor, it will hibernate instead of sleeping. If it is not plugged in to the monitor, it will sleep like normal.

I have a 15" MBP, 2.2 Ghz, running OS 10.8.2, with a USB mouse attached, as well as a USB HD and FW Time Machine disk, connected to the monitor via an Apple Thunderbolt-DVI adapter into a DVI cable, with both displays running. It doesn't matter which way the machine sleeps, they all yield the same problem. The console has no weird messages. And disabling sleep is NOT a viable option.

What is causing this abnormal behavior and how can I prevent it (without disable hibernation entirely)?



I followed the instructions to completely disable hibernate, and have run into an even worse  issue. When put to sleep attached to the DVI monitor, the machine will completely shut down. What will let my machine sleep normally?
First, try disabling hibernation (safe sleep) entirely:

sudo pmset -a hibernatemode 0

Then, to remove any trace of other previous hibernations, run:

rm /private/var/vm/sleepimage to free ~4 GB (in my iMac's case)

Should you ever want to turn Safe Sleep back on, run
sudo pmset -a hibernatemode 3

If you want to manage all of this with a simple System Preferences pane and it's worth four dollars for you, there's always SmartSleep.