[dylan604]

What kind of changes could you make to one clone that would still qualify it as a clone? If there are changes, it's no longer the same file. Even after reading the How It Works[0] link, I'm not groking how it works. Is it making some sort of delta/diff that is applied to the original file? That's not possible for every file format like large media files. I could see that being interesting for text based files, but that gets complicated for complex files.

[0] https://hypercritical.co/hyperspace/#how-it-works

[aeontech]

If I understand correctly, a COW clone references the same contents (just like a hardlink) as long as all the filesystem references are pointing to identical file contents.

Once you open one of the reference handles and modify the contents, the copy-on-write process is invoked by the filesystem, and the underlying data is copied into a new, separate file with your new changes, breaking the link.

Comparing with a hardlink, there is no copy-on-write, so any changes made to the contents when editing the file opened from one reference would also show up if you open the other hardlinks to the same file contents.

[dylan604]

ah, that's where the copy-on-write takes place. sometimes, just reading it written by someone else is the knock upside the head I need.

[MBCook]

That’s correct.