On 5/19/21 3:04 AM, tabris@tabris.net wrote:
Have you looked into blkdiscard? It is like fstrim, but it works on entire block devices. NOTE: technically this doesn't promise to wipe the contents, only mark all of the blocks as not caring about the contents. Some SSDs promise that subsequent reads will return all zeros, some do so only lazily (that is, ordering/scheduling of the effect vs read is not guaranteed), some may make no such guarantee at all. It remains the least effort way to prep an SSD for reformatting while producing the least number of writes.
As to hdparm, secure erase and the enhanced version aren't supported by all drives (there are ways to check, read the man page). I believe the enhanced version is supposed to clear/reset an encryption key, effectively scrambling the previous contents. I don't recall if this guarantees the disc will show all zeros or no. Probably is, as with discard, implementation defined.
Sent from myPhone.
Thank you very much tabris for your input. I will note your comment on this. I have been unable to have much time at my machine this week. Being able to note this will certainly help. --Regards