Re:WD Passport 4TB drives don't support WRITE SAME command
by kllrnohj on Thursday March 26, 2020 @04:23PM
(#22697588)
> Is there an alternative non-optional strategy for achieving secure delete
Issue normal data writes of blocks that are filled with zeros. The same way regular data makes it to the drive just fine will also of course work for data that's all zeros.
Re:WD Passport 4TB drives don't support WRITE SAME command
by jjoonathan on Thursday March 26, 2020 @05:54PM
(#22698378)
Oh, so WRITE SAME doesn't come with "no wear leveling" semantics? That makes emulation much more reasonable.
Re:WD Passport 4TB drives don't support WRITE SAME command
by kllrnohj on Thursday March 26, 2020 @08:01PM
(#22699253)
I think the only way to get "no wear leveling" is the ATA Secure Erase command. Which you only need for devices that do wear leveling in the first place which the drive in question doesn't anyway so it's a bit moot.
Re:WD Passport 4TB drives don't support WRITE SAME command
by pixl97 on Thursday March 26, 2020 @05:04PM
(#22697981)
Would that work on a filesystem that supports sparse files?
Re:WD Passport 4TB drives don't support WRITE SAME command
by throwaway373438 on Thursday March 26, 2020 @05:10PM
(#22698028)
We're talking about the filesystem driver itself issuing the write.
The above is a discussion about whether the filesystem driver or the block device driver would issue the SCSI commands.
This would never happen from userspace.
Re:WD Passport 4TB drives don't support WRITE SAME command
by tedunangst on Thursday March 26, 2020 @06:27PM
(#22698621)
Why would you need to overwrite blocks of a sparse file? Which blocks would you be overwriting?
Is there an alternative non-optional strategy for achieving secure delete (or revocation semantics of some kind)? If not, this is a fundamental capability that you can't paper over by slapping an abstraction layer on top any more than you could turn a 1TB HDD into a 2TB HDD with an abstraction layer. If so, it seems to me like the bug is very much in the hard drive / standards, not in the operating system.