Three-Pass: This is a DOE-compliant three-pass secure erase.Advanced recovery techniques could restore the data, but it would require a great deal of time and effort. Zero Out the Data: This erase method writes a single path of zeros to all locations on the selected volume or disk.
It doesn't scramble the file data, which means a recovery app may be able to resurrect the erased data.
7-Pass Erase: This method meets the security requirements of the U.S.The length of time this method takes depends on the size of the volume. It erases the volume's data by writing over it with zeros. Zero Out Data: This method provides a good level of security.It removes the volume's catalog directory but leaves the actual data intact. Don’t Erase Data: This method is quick but not secure.Options for OS X Snow Leopard and Earlier