Disk wiping

• To wipe an HDD by writing zeros to it:

# dd if=/dev/zero of=/dev/sdX iflag=nocache oflag=direct bs=4M

The average speed is above 100 MB/s, so 1 TB takes about 2-3 hours.

To print transfer statistics (to stderr):

# killall -USR1 dd

• To wipe a SSD by the ATA Security Erase command:

1. Make sure the drive is not frozen and support "enhanced erase":

# hdparm -I /dev/sdX

[...]

Security:

Master password revision code = 65534

supported

not enabled

not locked

not frozen

not expired: security count

supported: enhanced erase

3min for SECURITY ERASE UNIT. 3min for ENHANCED SECURITY ERASE UNIT.

[...]

Check that hdparm prints "XXXmin for SECURITY ERASE UNIT".