The phrase "very expensive computationally to create but can easily be re-made" seems like an oxymoron to me. Why do you need to cache them at all if they are very easy to re-make? Generally, the purpose of a 'cache' is to provide faster-than-normal access to data. You say you don't care about speed of access. Since you are talking about potentially a ~TB worth of data, seems to me that you're really just talking about perhaps a separate filesystem.