GNU+Linux command memo

Clear storage disk

Effacer les données d’un disque dur.

Ma société propose des services d’effacement complet ou de récupération de données ici.

My company offers services of storage deletion or data recovering here.

# dd if=/dev/urandom of=/dev/<sdb> bs=1M status=progress   (1) (2) (3)
75623301120 bytes (76 GB, 70 GiB) copied, 678,034 s, 112 MB/s (4)
1 Why urandom :
2 Change <sdb> for the correct storage device
3 bs=1M : the default block-size (512o) spoils perf. with modern hardware, more info here : dd buffer size.
4 Dynamic output line tracking operations thanks to status=progress
Modern disk hardware (such as SSD or USB keys) and modern filesystems may save data in places where you cannot delete them, so this process may still leave traces. The only safe ways of wiping data are the ATA Secure Erase command (if implemented correctly), or physical destruction.

To only destroy the MBR (Master Boot Record) :

# dd if=/dev/zero of=/dev/<sdb> bs=446 count=1

To repeat the process several time :

# for N in `seq 7`; do dd if=/dev/urandom of=/dev/<sdb> bs=1M status=progress; done;