Mark it inaccessible and write the new data over it in the next write cycle.

That doesn't work on SSDs, and the data might be even theoretically recoverable on HDDs : https://security.stackexchange.com/questions/12503/can-wiped... > Therefore, you should assume there is no reliable way to securely erase individual files on a SSD; you need to sanitize the whole drive, as an entire unit.

There's a reason why when security is deemed important, the storage is physically destroyed instead.

I meant for the sake of data protection, not for forensics. You start with all ones and gradually deplete your ability to write ones over time in electron charge memories such as SSDs.

This is not about companies following best practices but about what is going to happen when some of the supposedly deleted data pops up again, as it eventually will.

Will a judge that is clueless about how computers really work consider that as a GDPR violation or not ? As deliberate or not ?

If you disable wear levelling, you could force it to end in a final all-zeros state.