There's another option in addition to the methods described in the Tip of the Night for February 26, 2016 for data wiping or sanitization. Secure Erase just makes one pass, writing either a 1 or 0, but takes place within the drive excluding the possibility that anything will be missed, and operating more quickly than other methods of data sanitization. The methods referenced two nights ago are block erase techniques that use installed software to overwrite data. These methods can be vulnerable to malware. Secure Erase is firmware, software that is embedded in hardware. It's another option in addition to the Format Drive command in a data storage system. However Secure Erase can only function on an entire drive, not an individual folder.
Secure Erase does not work with SCSI hard drives. The enhanced version of Secure Erase makes multiple passes in its overwriting process using predetermined data patterns set by the manufacturer of the drive, and includes reallocated disk sectors, or those no longer used because they had errors. Secure Erase can wipe 100 GB of data in a few hours with greater security, than block erase techniques which take 1 or 2 days and offer a weaker guarantee that data can't be recovered. The enchanced version of Secure Erase works even faster.
You an use freeware provided by the University of California, San Diego's Center for Memory and Recording Research to run the internal secure erase command of a drive. Note that it will not work with either SCSI or USB drives, only SATA or ATA drive. See the Litigation Support Tip of the Night for January 22, 2016.