
Then we find out that Apple has removed this option since they deemed it ineffective. Keep in mind that the latter two options take longer to complete, because they are performing the same overwrite task either 3 times or 7 times. Ive read threads saying that you can secure erase your SSD drive by command+R booting and using the Disk Utility and then selecting the 'security options' for a secure erase.
#SECURE ERASE HARD DRIVE MAC FREE#

#SECURE ERASE HARD DRIVE MAC MAC OS X#
Erasing Free Space on Hard Drives in Mac OS X This option is not available for flash-memory based SSD models (like those bundled within the MacBook Air, Retina MacBook Pro) because those drives use the TRIM function to quickly remove and recover blocks instead, which has the side effect of automatically preventing file recovery fairly quickly – often within 10 minutes of emptying the Trash.

This only works on traditional hard drives of the spinning platter variety, which is typical for MacBook Pro, Mac Mini, and iMac models, and is the case with most external hard drives used for backups. The Mac OS X Disk Utility app provides an ability to erase free space on traditional hard drives, which overwrites vacant disk space on the drive to prevent any potential recovery of deleted files (that is, files that have been removed traditionally, rather than through secure methods).
