One of the best ways to keep your data secure is by only writing data to an encrypted hard drive. On a standard drive, it[he]#039[/he]s possible to view data just by mounting the drive as if it were a thumb drive, and it[he]#039[/he]s even possible to display and recover even deleted data with tools like Scalpel and Testdisk.

Source: LXer – 4 Linux tools to erase your data