Sleep = hibernation ?

Discussion in 'Mac Basics and Help' started by novetan, Dec 9, 2010.

  1. novetan macrumors 6502

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    Sep 3, 2010
    #1
    In Window there are options for sleep and hibernation. I don't see any hibernation in Mac. Are they the same?

    Is it ok to put to sleep instead of shutting down and carry around?
     
  2. simsaladimbamba

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    #2
    Sleep is keeping the RAM under power, thus the content of the RAM is safe.
    Hibernation copies the content of the RAM onto the HDD and after that shuts everything down, the RAM is not powered. On awakening the PC, the RAM is being filled with the content it has written onto the HDD.

    Therefore using Sleep is loads faster (one to two seconds) compared to Hibernation (30 seconds plus).

    And it is safe to move the Mac around while asleep, as the HDD is parked and only the RAM is powered.
     
  3. sammich macrumors 601

    sammich

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    #3
    Sleep = stops all equipment, and supplies power to just the RAM so that everything is where you left as you slept it.

    There isn't a 'hibernation' in OS X, as much as there is a 'safe sleep' where RAM is copied onto your hard drive as you sleep, so that if there is loss of power for whatever reason, your computer state is saved as you put it to sleep.

    Hibernation is a combination of shutting down and OS X's safe sleep.
     
  4. maflynn Moderator

    maflynn

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    #4
    Actually, its the exact same thing, apple calls it safe sleep, MS and the world calls it hibernation.

    Heck in changing the sleep options you invoke within the terminal
    pmset hibernatemode <value>

    So even then apple is using the term hibernate :)
     
  5. sammich macrumors 601

    sammich

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    #5
    Ah, but I thought there was a distinction between safe sleep and hibernate: in Windows, hibernate actually puts the machine into a much lower power state than Windows' 'standby'. Whereas 'safe sleep' on OS X is simply the normal 'sleep' with the added RAM state being saved.

    IIRC, Windows Power/Battery control panel tells you how much standby and hibernate time you have left if you activated them now, and hibernate is much longer. From what I gathered back then, also, is that hibernate will lose the state if battery runs out, unlike safe sleep, which keep a state forever.
     
  6. novetan thread starter macrumors 6502

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    #6
    What is safe sleep? Something new to me. Its it an additional plug in? I can see only restart, sleep or shut down.
     
  7. wrldwzrd89 macrumors G5

    wrldwzrd89

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    #7
    Safe sleep doesn't have a user interface option to invoke directly. It activates automatically in notebook Macs when they have been sleeping and the battery is low.
     
  8. sammich macrumors 601

    sammich

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    #8
    Just a small correction, if I may:

    Safe Sleep is on by default. It writes the entire contents of your RAM to the hard drive EVERY TIME you put the machine to sleep (you'll see this as the machine takes about 10-15 seconds longer before the sleep light starts 'snoring').
     
  9. Dalton63841 macrumors 65816

    Dalton63841

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    #9
    If you just NEED a UI to handle your sleep modes, check this out: http://www.jinx.de/SmartSleep.html

    You can set the sleep mode with this preference pane, and the last time I used it it had an option for "smart sleep" which if I remember correctly meant normal sleep, but anything below a "user chosen" battery level would make it use safe sleep.
     
  10. Azathoth macrumors 6502a

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    Sep 16, 2009
    #10
    No, it's not the same:
    Windows:
    Sleep: set processor to sleep state, keep power to RAM contents (RAM refresh)
    system power usage typically 0.1W-0.5W

    Hibernate: store all memory contents to a file on the HDD and completely power off the system. Read RAM contents back from file upon "de"-hibernate.
    system power usage: essentially 0. No data is lost when removing the battery.

    OS X:
    by default OS X does the above Sleep when closing the lid, but in parallel it also stores the RAM contents to HDD, so that if system power is lost (e.g. Sleep for a couple of days drains to battery to 0), then the system state can be resumed from the Hibernate file automatically.

    Advantage: user doesn't need to think
    Disadvantage: 10s delay when closing the lid whilst the HDD is still in use

    Because I have an SSD, I use the SmartSleep control panel item (oops, I mean System Prefs), to tell it not to write a hibernate file - saving disk writes (and for mechanical HDD based systems, it means that you can move the machine instantly when you close the lid).
     
  11. wrldwzrd89 macrumors G5

    wrldwzrd89

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    #11
    I did not know it worked that way. Thanks for the information - that makes sense, otherwise how would the Mac be able to power down the RAM safely?
     
  12. Consultant macrumors G5

    Consultant

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    Jun 27, 2007
    #12
    OS X uses a hybrid mode.

    When sleep (shutting lid), RAM is keep alive, but content of RAM is copied to harddrive. So you get both instant on and protection against loss of power.

    No need to choose useless windows "options".
     
  13. ActionableMango macrumors 604

    ActionableMango

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    Sep 21, 2010
    #13
  14. RedTomato macrumors 68040

    RedTomato

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    #14
    Lots of confusion in this thread.

    OSX - > on -> sleep -> (if battery very low) -> hibernate.

    Close lid = Sleep = some battery drain, but low = can leave overnight or transport around.

    (I take my laptop to work and back everyday, and I only reboot about once a month)

    Battery becomes very low = hibernate (this happens even if the laptop is asleep at the time) = copy RAM to HD = battery drain = can last forever.

    If laptop is on, and you let battery go to zero, it will go to sleep, then a few minutes later go into hibernate.

    Interesting factoid - Mac laptops have a small backup secondary battery that will let you change the main battery without shutting down. Close lid, let it finish going to sleep (light starts pulsing), take battery out, put new one in (or old one back in if testing), open lid, and it wakes instantly again. You have a minute or two to change batteries.
     

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