[Discuss] CoW for Ext4?

[Dan Ritter]

Dale R. Worley wrote: 
> I've discovered how useful it is to take a copy-on-write clone of a disk
> tree when I want to repair application data consisting of lots of large
> files.  (Virtual Box VMs and Apple Music libraries are the cases I've
> used.)  Apple's APFS handles this easily.  I hesitate to ask, but has
> CoW support been proposed for Ext4?


You can't add CoW as a feature; it's a basic structure of the
filesystem. I suppose it might be possible to write something
that could write a disk format that ext4 would be able to read,
but at that point it would be ext5, no?

You can use ZFS (recommended), btrfs (I wouldn't recommend it),
bcachefs (maybe in 2-3 years), or xfs (can use CoW for data, not
for metadata, has issues).

-dsr-