MBP often won't wake after sleep.

MY WORKAROUND:
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Short Answer:
= Find a way to get the computer to write a new sleepimage

Long Answer:
= Read long answer below.
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Situation:

= MacBook LCD turns off immediately after waking from sleep. (I use hibernate mode 5 because I use secure virtual memory (see end of post)) Even though the LCD is off, the OS is still fully functional.

From When:

= From what I can tell, this started happening:
. = when I switched from hibernate mode 7 to hibernate mode 5
. = (less likely) after I upgraded to OS X 10.6.6

What DID NOT work:

= re-sleeping and re-awakening the laptop
= setting a hot corner to sleep the display, and then mousing in and out of the designated corner
= changing the display resolution

Suspicion:

= After reading how some people got their LCD to work again after deleting their (corrupted?) sleepimage ( /private/var/vm/sleepimage ), I tried to think of a way to have the computer create a new sleepimage without rebooting the machine, or, without shutting down the machine, then manually deleting the sleepimage files from another computer.

Idea:

= Do something on the computer that creates so much activity that the sleepimage would have to be updated to reflect the changes.

Test (from my dimmed/blacked out MacBook):

= I launched my virtualization software (VMWare Fusion) and then powered up a virtual machine (an old copy of MS Windows). Once Windows was up and logged into, I powered it back down. This usually creates a lot of disk activity on my computer (I know this from harddrive backup logs).
= I then quit out of VMWare Fusion and put the laptop to sleep by closing the lid (which forces a new sleepimage to be written, if necessary).

Result:

= After the laptop was fully asleep (indicator light turns off (deep sleep)), I re-awakened the laptop. The LCD stayed on after the wake up process

END OF WORKAROUND:

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Information about Sleep mode: (redo if PRAM/NVRAM is reset)

• Quick: No hibernation features are enabled. Also known as mode 0.
• Safe: Hibernation features are only used when the computer runs out of battery power. Also known as mode 3 or 7.
• Deep: Full hibernation. Also known as mode 1 or 5.

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• 0 (quick): Default sleep behavior on most Apple computers. RAM is still powered on while sleeping. Wake up is fast. Safe sleep is disabled.
• 1 (deep): Hibernation behavior. System is totally shut down while sleeping. RAM contents are dumped to disk. Wake up is slow.
• 3 (safe): Default behavior on Powerbook HD and later computers. RAM is still powered on while sleeping. Wake up is fast. Safe sleep is enabled, so RAM contents are also dumped to disk before going to sleep.
• 5 (deep): Same as mode 1 for systems with secure virtual memory (System Preferences > Security).
• 7 (safe): Same as mode 3 for systems with secure virtual memory (System Preferences > Security).

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Commands:
sudo pmset -g | grep hibernatemode;
sudo pmset -a hibernatemode [#];

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Message was edited by: kevinx

@kevinx
It seems that the hibernatemode information you are providing is inaccurate. "man pmset" states, among other things:

"We do not recommend modifying hibernation settings. Any changes you make
are not supported. If you choose to do so anyway, we recommend using one
of these three settings. For your sake and mine, *please don't use any-*
*thing other 0, 3, or 25*."

Just in case someone tries to follow the information.

BR/apan

Clarification:

- I am not recommending that anyone change their hibernate mode to fix their display problem or for anything else.

- My recommendation for a dimmed display after sleep was to create disk activity in some way.

- My own hibernate mode was suspected as a cause for sleep/wake irregularities so my settings were included in the post.
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//
// More on alternate hiberation modes:
//



// Apple document on secure virtual memory:

Preventing information in memory from being read:
http://docs.info.apple.com/article.html?path=Mac/10.6/en/11852.html



// 2006 article on use of alternate hibernation modes, including ones for secure virtual memory (since resolved):

Set newer portable Macs' sleep mode:
http://www.macworld.com/article/53471/2006/10/sleepmode.html



// 2007 article on conflict between hibernation and secure virtual memory (since resolved):

Safe Sleep Revisited:
http://db.tidbits.com/article/9115



// 2008 articles on conflict between hibernation and secure virtual memory (since resolved):

MacBook’s Hibernation and Secure Virtual Memory:
http://www.johankool.nl/2008/03/macbooks-hibernation-and-secure-virtual-memory/

A Bit More About Hibernation
http://www.johankool.nl/2008/03/a-bit-more-about-hibernation/



// Apple manual page for pmset:

pmset(1) Mac OS X Manual Page
http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/ man1/pmset.1.html

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I've reverted from mode 5 back to mode 3 based on this information.