Geek talking

Pinoy geek talking about everything under the sun

Safe sleep

Posted by rom on November 13, 2005

Ever wondered why your battery gets drained when you are on Sleep mode? Well, the answer to that is how the Mac manages your data whilst in Sleep mode. By default, it keeps everything on RAM and powers it whilst at sleep. This ensures that almost instantaneous response when waking up the Mac. Contrast this against Windows and Linux, both OS saves your data to your hard disk and then turns off your computer.

On boot, the Mac just resumes from RAM. Since RAM is much faster than your hard disk, it goes to active mode faster than any Windows or Linux computer. However, your Mac eats up power whilst asleep. New powerbooks (October 2005) have a mode called Safe Sleep – this functions the same way as Windows or Linux. It saves the state of your computer on your hard disk. Boot-up is slower, of course, since it restores everything from hard disk.

Anyway, I tried the hack on my 15″ 1.67Ghz powerbook (January 2005) and although I got confused as to how it is supposed to wake up (you use the power button instead of the usual “any” key wake up), it works pretty well. Going to sleep takes 3 seconds, whilst waking up is around 31 seconds. Not bad, I must say. The benefit is that no power is used, the sleep indicator is turned off (no glowing light in your otherwise dark hotel room when you are catching some sleep as well) and the computer does not wake up when your mouse detects motion. I like it!

I tried it on my 12″ powerbook as well (rev C) and it works, too. Just that I don’t know how the wife will use it so I set it back to the “old” sleep mode settings.

BTW, it needs 10.4.3. 😀


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