Is using shred to wipe Linux SSDs safe?

Solution 1:

Before resorting to shred, see if the drives support Secure Erase, which will make sure that all possible regions on the drive are erased. Despite all the talk about SSDs supporting Secure Erase, quite a few HDDs support it and thus it is easy to believe that SSHDs would as well.

# hdparm -I /dev/sdX
 ...
Security: 
    Master password revision code = 65534
        supported
     ...
        supported: enhanced erase

 # hdparm --user-master u --security-set-pass p /dev/sdx
  ...
 # hdparm --user-master u --security-erase p /dev/sdX
  ...

Note that there are further requirements for having the drive allow the Secure Erase operation; see the above article or similar.