Isn’t it beautiful when using your MacBook / MacBook Pro, you just close the lid and the computer instantly goes into the sleep mode? Even better, you just open it and in a few seconds you are where you were before.
And the coolest of all is when you’re in a hurry, you just shut the lid, put the computer into the bag and run downstairs, or jump on your bike and off you go. Right ?
What I just described above is a big no-no if you have a MacBook, MacBook Pro or the very last model PowerBook (late 2005).
The reason for this is SafeSleep, a technology Apple introduced to all portable computers since October 2005.
What happens when ‘normal’ computers are put into sleep mode is that the memory is supplied with a very small amount of power to keep its content ‘alive’. When you wake up the computer, it will be in the state you left it before. But in case of a power failure, or battery going completely flat, the memory will lose the power and therefore your data is gone. Game over.
Apple’s SafeSleep works similar to this but it has something else for when the disaster strikes. When you close the lid the computer goes to sleep mode, but not instantly. Firstly, it copies entire content of its memory onto the hard drive, and then goes to normal sleep mode. Once you wake up the computer, the memory is already loaded and you can use it straight away.
If you lost the power/battery, once you power on the computer again, the memory content that was stored onto the hard disk will be loaded, so you take it from where you left it before. You will see the black and white screen while this is happening, so don’t panic, your display is just fine.
And this is exactly where the problem is. You must not move your computer while the data is written to the hard drive. You have to wait until the sleep light on the front starts pulsing. This may take anything between 10 and 30 seconds, depends on the amount of memory you have installed in your computer.
This is what Apple’s MBP manual states:
Warning: Wait a few seconds until the white sleep indicator light on the display latch starts pulsating (indicating that the computer is in sleep and the hard disk has stopped spinning) before you move your MacBook Pro. Moving your computer while the hard disk is spinning can damage the hard disk, causing loss of data or the inability to start up from the hard disk.
So, you wonder – what difference does it make, Apple notebooks have the Sudden Motion Sensor and will prevent any data loss or disk damage ?
Wrong again! The Sudden Motion Sensor has no effect in this situation, so you’ll be better off to leave your computer to finish the job it has to do.
Update 03-Aug-2008: There is a glimpse of hope that you can still save your data and get your hard drive running again, read my article How to revive a dead hard drive.