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?

Solution 1:

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.

Solution 2:

~~Well, it's hard to be sure since you haven't given the full specs of your setup~~

I am guessing the problem is because your MBP has 2 GPUs ("graphics cards") (a discrete one and an integrated one) and there's some issue with the discrete one going to sleep that is causing the OS to give up on it.

Obviously the first option is to disable sleep, but not really a solution.

Next, check the Console (All Message) and look for any messages that happen when you put the computer to sleep. I expect you will find some sort of error message that may help us figure out exactly what the problem is.

If the console messages don't help, then I recommend you install gfxCardStatus and see if it makes a difference whether you are using the integrated or the discrete GPUs. If it's only a problem with one then you can stick with the other, or complain to Apple that the GPU is broken and see if they will fix/swap the hardware.