[qual]

>I don't need to mind about this with encrypted data.

I'm not sure if I wasn't clear or if you didn't read my comment correctly.

Encrypting is not enough to prevent data recovery if data was written to disk prior to encrypting it.

In other words, if you want to be 100% sure about your data being safe, you must encrypt first (when the drive is brand new), or you must physically destroy the drive.

[Helmut10001]

Yes, I understood - but this has nothing to do with encryption. Data that is encrypted is save. Any data that is not encrypted (or was not encrypted) would offer an attack surface. Since I use ZFS for all my data, all my data is encrypted from Minute 1 of a new hard drive.