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, support "enhanced erase" and hdparm prints "[number]min for SECURITY ERASE UNIT":

   # 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.

   [...]

2. Set a user password (this password will be cleared on the next step, so the exact choice does not matter):

   # hdparm --user-master u --security-set-pass foo /dev/sdX

3. Issue the ATA Secure Erase command:

   # hdparm hdparm --user-master u --security-erase foo /dev/sdX