Julian Assange and a couple of others developed a file stem called Rubberhose to avoid this problem. All of the filesystem structures, data, and free space are

Julian Assange and a couple of others developed a file stem called Rubberhose to avoid this problem. All of the filesystem structures, data, and free space are indistinguishable from noise without the decryption key. The system always sets up some portion of the filesystem as unusable space that's initialized to noise. This space may contain another Rubberhose instance, which would also have some unusable space in it. If you're tortured to keep revealing keys to deeper and deeper volumes, eventually you're going to hit a point where there are no more volumes, but you can't prove it. I think the original threat model was someone willing to torture you, but willing to accept plausible deniability once you'd revealed some moderately sensitive information. In reality, if someone is willing to torture you a couple volumes deep, there's a good chance they're going to just keep torturing you forever. Rubberhose may still work in this model, since in theory the promise of avoiding torture loses most of its power. The downside is that once you format a partition with Rubberhose, you're resigning yourself to being tortured forever.