[pixelbeat]

Note mv tries reflink by default (when moving files across BTRFS subvols) since doesn't need a separate copy of the data. Now as storage systems evolve there are less guarantees that one does get multiple copies, with deduplicating at lower layers etc., and therefore cp may change at some stage to reflinking by default, especially as clone_file_range() moves to the VFS level. Actual data redundancy would then achieved at a higher level with separate file systems, devices, data centers, ... where arguably it needs to happen now anyway.