The way I understood it, was that if more than a single file existed on a server that were identical, it would replace the copies of the file with a symlink to the original. Then, if you made a change to one of the files, it would remove the link and have the changes saved as the file. For instance, if you have files A, B, and C in different directories, but are all exactly the same, it would replace two of those files with a symlink to the third. If B and C were symlinks to A, and A was changed, the symlink from B or C would point to the other, which would revert to a full copy of the original file, and A would be the changed file.

The end result is that you save space when there are identical files on a server. As much as this was touted, I have never seen it. Go figure. I think I'll just stick with Slack .