Yes. Hyperspace is finding the identical files and then replacing all but one copy with a reflink copy using the filesystem's reflink functionality. When you a

Yes. Hyperspace is finding the identical files and then replacing all but one copy with a reflink copy using the filesystem's reflink functionality. When you asked about the filesystem, I assumed you were asking about which filesystem feature was being used, since hyperspace itself is not provided by the filesystem. Someone else mentioned[0] fclones, which can do this task of finding and replacing duplicates with reflinks on more than just macOS, if you were looking for a userspace tool. [0]: https://news.ycombinator.com/item?id=43173713 https://news.ycombinator.com/item?id=43173713