HDPARM secure-erase uses the OPAL standard which ensures unused bad blocks, that the drive normally ignores, are erased too. TRIMMING only cleared blocks normal

HDPARM secure-erase uses the OPAL standard which ensures unused bad blocks, that the drive normally ignores, are erased too. TRIMMING only cleared blocks normally accessible for reading/writing. It’s not as low level… But as someone has mentioned you can just enable encryption and forget the keys…most all SSDs are encrypting from new…user and master keys just have to be set.