MBP: Safe Sleep - Lovin IT

Discussion in 'Mac Basics and Help' started by shadowfayre, Mar 16, 2006.

  1. shadowfayre macrumors member

    Joined:
    Jan 17, 2006
    #1
    Well, I am a recent Mac convert. I have work with PC (Win32) units for many of years. Let me first say I love the 'safe sleep' on these MBPs. I have used several laptops; including Thinkpads, where there are two modes: suspend and hilberation. In suspend, the computer is on, although not using alot power enough to drain the battery in a day. Second to that, I have pulled laptops out of carrying bars in suspend mode several times, to find that the unit and bag is like a dry sauna (aka HOT!) Hiberation, AH! Under Windows, half of the time, if it actually gets out of hiberation correctly (no BSOD or lockups, etc) it takes just as long to power up then from a cold boot (minus POST).

    Now that said, Mac seems to have it right! I close the lid 5 mins later the laptop goes into the safe sleep and begins to cool down (fans turn off etc). Dropped it in a carrying bag to take it out later, nice and cool. No heat in the bag.

    And the really cool thing, near instant on! It is really a bit freaky actually. I still hesistate to put the MBP in my bag, just remembering how a laptop HDD fried in a past due to over heating. And since it comes up near instant, it is all the better.

    I read that the RAM is left on, which explains the speed and many people have asked about the safety regarding placing a laptop in the bag in this mode, so I am not asking that again. Just a bit of praise from a PC guy. :)

    Now if I can get only get on my Windows DOMAIN ;)
     
  2. Anonymous Freak macrumors 601

    Anonymous Freak

    Joined:
    Dec 12, 2002
    Location:
    Cascadia
    #2
    First, I think you're confusing terms.

    Sleep on the Mac is the same as Standby on Windows. Both continue to power RAM. Both consume some amount of power. But both modes generate almost zero heat. My 12" PowerBook would often not be turned all the way off for a month at a time, only going into sleep mode. My MacBook Pro hasn't been all the way off for more than an hour since I opened the box on February 24th. It is 100% safe to leave the computer this way in any location that it is safe to have it off in. (i.e. don't leave it on your car dashboard in the sun, but in any computer bag should be fine.)

    Safe Sleep on Mac is the same as Hibernate on Windows. Both save the state of the machine to disk, then turn completely off. When you restart, the hardware does indeed go through POST. Then the OS bootloader starts up, and sees this hibernate image on the hard drive and loads it instead of loading the normal boot procedure. This can be sped up by having a faster hard drive, and/or (ironically) by having less memory.

    So a desktop computer with a 15,000 RPM hard drive and 256 MB of RAM will wake from Hibernate significantly faster than a laptop with a 4200 RPM hard drive and 2 GB of RAM.

    For example, if you install Windows on your new MacBook Pro, (as I'm going to do tomorrow,) waking from Hibernate in Windows should take the exact same amount of time as waking from Safe Sleep in OS X on the same machine.
     
  3. shadowfayre thread starter macrumors member

    Joined:
    Jan 17, 2006
    #3
    Standby is just a newer name of suspend (I believe that was what it was called in Windows 2000). And unless I am confused (which is totally possible; comes with old age), it still is the same issue. When I put my Thinkpad in Standby/Suspend it still gets hot in a bag, if left for a long period of time (hours).

    So far I have not had my MBP go into Safe Sleep, or at least I am not aware of it. Everything I have opened the lid, it is there ready for me. I saw a post about memory being left powered and that would in deed explain how it comes back so quickly and still faster than Windows. This may have to do with the way OSX handles memory?
     
  4. fradac macrumors regular

    Joined:
    Oct 24, 2003
    Location:
    Atlanta, GA
    #4
    ya i love that i can put my laptop to sleep whenever i want

    now getting on the PC domain, i use my powerbook at work and its on the company domain and i can log into the company network, if you wanna know how, send me a PM i can walk you through it
     
  5. shadowfayre thread starter macrumors member

    Joined:
    Jan 17, 2006
    #5
    Yeah, I plan on workign on the Domain issue over the weekend. I have a filling it is a DNS issue. The error is a symbol link is invalid or something like that. I can ping the address and see it in the 'finder?' but can not connect. I downloaded the document from MS regarding connecting a Mac to a Win server; however if I still have problems I will either PM you or post a message here in these great forums!
     
  6. dr_lha macrumors 68000

    Joined:
    Oct 8, 2003
    #6
    Nope, I'm afraid you're wrong. Safe sleep is different from Hibernate on Windows in the fact that it doesn't power off the computer, and it is not a seperate option from regular sleep. Here is how it works:

    Every time you sleep your computer "Safe Sleep" saves the memory state to HD. If the computer remains powered then opening the computer lid (or whatever) will make the computer wake as it normally does. However if the computer loses power (e.g. the battery gets removed) then when it is powered up again it will use the safe sleep file to bring the computer back to life as it was when sleeping.

    Unlike Hibernate on Windows its use is utterly transparent to the user. It "just works". The only real loss of functionality is that you can't force your computer to power off after sleep without somehow removing it from its power source. Well, not from the GUI anyway, it can be done from the command line.
     
  7. Anonymous Freak macrumors 601

    Anonymous Freak

    Joined:
    Dec 12, 2002
    Location:
    Cascadia
    #7
    edit:Sorry, but you are the one that is incorrect. See last paragraph Macs that support Safe Sleep do not save the contents of memory to the hard drive unless the battery is 'dangerously low' (i.e. low enough that it won't let you wake it up from 'normal' sleep.) THEN it turns on, saves memory image to HD, and shuts off. Just like Windows computers do when hibernating, if their power settings are configured correctly. It's just that on Windows computers, you can also CHOOSE hibernate mode, whereas on the Mac, it's not a choice. It does it when it feels like it, and you have no input.

    See Apple's documentation on Sleep or Safe Sleep for more info.

    As for Standy/Suspend/Sleep. They are all different names for the same mode. Apple's new Intel Macs use the EXACT same technology to go to 'Sleep' that Windows computers use to go into Standby/Suspend. If you install XP on an Intel Mac, and put it in Standy mode, it will use the exact same amount of power, and generate the exact same amount of heat, as OS X in Sleep mode. There is no technological difference. Standby/Suspend on Windows continues to power RAM, just as Sleep on OS X does. OS X wakes from sleep faster than Windows simply because it was better written to handle sleep better.

    edit: Hrm... After more searching on the Apple Support site, I did find an article on How to swap the MacBook Pro battery, which does mention that "As the system goes to sleep, it will save the contents of the RAM (Random Access Memory) to the computer's hard drive." I guess this is a new thing, as I know it doesn't do this on my Safe-Sleep-enabled 12" PowerBook. (i.e. if I put it to normal sleep, then take out the battery, it won't 'wake from safe sleep' when I power back up, it will just turn on like it had been turned completely off with no safe sleep.) You learn something new every day...
     
  8. dr_lha macrumors 68000

    Joined:
    Oct 8, 2003
    #8
    EDIT: as you've seen the error of your ways... ;)

    Maybe your PB works differently because the 12" PB does not officially support Safe Sleep. I know it works on a 12" PB, but you had to do some hacking to get it to work right? Perhaps you set it to a different mode than the default way Safe Sleep works?

    Note: I also have a 12" PB with safe sleep, and it does work the that Apple doc suggests.
     
  9. Anonymous Freak macrumors 601

    Anonymous Freak

    Joined:
    Dec 12, 2002
    Location:
    Cascadia
    #9
    Yeah, I have a rev.a, which doesn't officially support it, but can be forced to use it.

    I can make it use Safe Sleep instead of normal sleep, or the 'default' mode where it will go into safe sleep if the battery gets too low that it won't wake up from normal sleep.
     

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