I'm not aware of an option (?) to overwrite fingerprints of images, so I guess I don't - I do have lots of files in the fingerprints data bases. The MD run is 1 fs time-step, so it's 25,000 images (consider here the potential is trained in atom-centered mode). In the primes data base which takes those 400GB there are two kinds of files: the ones that were created during the training phase and are about 2MB each, and the ones that were created during the MD run which are about 17MB each. Also, the training images contain 128 atoms.