FWIW this is similar to Apple's "sparse image bundle" feature, where you can create a disk image that internally is stored in 1MB chunks (the chunk size is prob

FWIW this is similar to Apple's "sparse image bundle" feature, where you can create a disk image that internally is stored in 1MB chunks (the chunk size is probably only customizable via the command line `hdiutil` not the UI). You can encrypt it and put a filesystem on top of it.