Copies, clones and backups are three different things. Here their differences are explained with examples from APFS and modern macOS.
copy
Track down all those duplicated files, and you could save yourself loads of disk space. Rather, you used to be able to. Why this doesn’t work so well now.
How can it take over 5 hours to back up 79 GB of files to a network share? That’s an average transfer rate of 4 MB/s, probably slower than your Internet connection.
APFS can ‘clone’ files when copying or duplicating them within the same volume. But how can you tell whether any given file is a clone?
Unlike file data, metadata has varying persistence. Some is ephemeral, others sticky. macOS has inbuilt mechanisms for managing the persistence of extended attributes.
How these fundamental features work in macOS, using the pboard daemon and UTIs. With full log transcripts too.
What happens when you copy a large file to the same volume, or duplicate it, on the same APFS volume? Here are the answers.
All about textClipping and pictClipping files: what they are, and how to access the data within them.
Diagram summarising how Finder Aliases work, including their resolution. And how to confuse QuickLook thumbnails.
Finder Aliases can update their path information when they are resolved. Also some differences between Aliases and Bookmarks.
The Eclectic Light Company 