3 Replies Latest reply: Dec 4, 2012 4:36 PM by todivefor
todivefor Level 1 Level 1 (0 points)

I am new to the Macbook Pro having come from an iMac.  I don't fully understand sleep.  Sometimes when I open my MBP, it fires right up to where I was.  At other times, it starts up in a gray display with progress blocks at the bottom that eventually gets to where I was.  It's almost like sleep vs hibernate.  Can someone please explain what is happening?

MacBook Pro, OS X Mountain Lion (10.8.2), mid 2012
  • 1. Re: Macbook Pro sleeping
    Courcoul Level 6 Level 6 (11,470 points)

    When it starts right up, means it was sleeping. When the gray bar appears, means it was hibernating. Hibernation is a fallback measure these computers have. When you close the lid, the system copies all the RAM contents onto a special file on disk, called the sleepimage, then proceeds to put all components into a low-power or off state as well as stopping and parking the drives.


    When you open the lid, the firmware checksums the RAM. If no errors are found, the contents are deemed undamaged and control returns using what's found there; this is an sleep recovery. If the contents were changed/corrupted/erased, they are invalidated, wiped clean and the sleepimage is copied over before returning control; this is a hibernation recovery.


    Why would the RAM contents go bad? Usually cause the battery flatlined due to excessive time sleeping. After all, keeping the RAM barely alive consumes power and the battery will discharge.

  • 2. Re: Macbook Pro sleeping
    sanjampet Level 5 Level 5 (7,550 points)

    try quitting all applications before putting it to sleep.



  • 3. Re: Macbook Pro sleeping
    todivefor Level 1 Level 1 (0 points)

    Thank you both for your information.  Very informative.  I guess whether you sleep/hibernate is not selectable, but based entirely on whether/not sleep was successful?


    Having to quit all applications prior to sleep seems to defeat the purpose of this function.