Chris Mason and the btrfs team are clearly talented. But the initial excitement of btrfs has sadly dissipated and its promise as the next generation Linux fs remains unrealised. It now feels a bit jaded and the momentum is spent.
I suspect many have lost patience with the promise of COW and unfortunately for bcachefs this history will cast a shadow on its development and potential.
Database performance remains problematic on COW and while things like snapshots and adhoc disk and volume management are interesting even exciting one soon realises unless one has a pressing need they are just nice to have. Eventually boring ext4 ticks all the boxes and one may as well forget about the fs and focus elsewhere.
I don't think COW in general is a big issue for databases. You can get pretty good performance for ZFS (very stable and consistent behavior), for example. The COW is not free, of course, but you get interesting features in return, and if you need them (e.g. snapshots), it's usually much better than LVM + non-COW filesystem.
The fact that some COW filesystem perform poorly does not mean all COW filesystems do.
I suspect many have lost patience with the promise of COW and unfortunately for bcachefs this history will cast a shadow on its development and potential.
Database performance remains problematic on COW and while things like snapshots and adhoc disk and volume management are interesting even exciting one soon realises unless one has a pressing need they are just nice to have. Eventually boring ext4 ticks all the boxes and one may as well forget about the fs and focus elsewhere.