Format storage drive for Mac step 4: Choose a security option
Click the Security Options button towards the bottom of the main window. This will bring up another window that enables you to choose how you'd like the drive to be formatted, with a slider ranging from Fastest to Most Secure.
Fastest will erase the drive by removing the header information, but will leave the underlying files intact, although they will be hidden. This means you or someone else could resurrect the files easily using data-recovery software, which isn't necessarily a good idea. For a fresh install of OS X, we'd recommend you move the slider to the second option where it says "This option writes a single pass of zeros over the entire disk." This will overwrite the entire drive once.
For higher security, continue moving to the slider to the right. The next step will give you the option to overwrite the drive three times. Moving it the entire way to Most Secure will overwrite the drive seven times - but you'll have to wait quite a while (depending on the size of the drive) before it will be available for you to use again.
Format storage drive for Mac step 5: Format the drive or USB
It's finally time to click the Erase button. Now go and do something else, like gardening, or a puzzle. Or spend some time with your friends and family. Formatting a drive can take a while, especially if it's large and/or you've chosen one of the most exacting Security Options. A progress bar will show how the formatting of your drive is going and how long, roughly, it will take to complete.
After a little while your formatted drive will finally be ready for you to add new files to. Tremendous stuff this technology, isn't it?
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