OS X Mountain Lion: What is safe sleep?

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What is safe sleep?

Some portable Mac computers have a feature called “safe sleep.” With safe sleep, each time the computer goes to sleep, the current state of the computer is saved on the hard disk, including open apps and open documents. Safe sleep prevents your information from being lost if the computer is completely shut down during sleep, which could occur if the battery runs down or is replaced.

If your computer needs to read the saved state when it wakes up, a progress bar appears until your computer is ready to use.

Published Date: Sep 4, 2015