I've had my own bad experiences with Btrfs (it doesn't behave well when close to full), and my intuition is that Facebook's use of it is in a limited operational domain. It works well for their use case (uploaded media I think?), combined with the way they manage and provision clusters. Letting random users loose on it uncovers a variety of failure modes and fixes are slow to come.
On the other hand, while I haven't used it for /, dipping my toes in bcachefs with recoverable data has been a pleasant experience. Compression, encryption, checksumming, deduplication, easy filesystem resizing, SSD acceleration, ease of adding devices… it's good to have it all in one place.
On the other hand, while I haven't used it for /, dipping my toes in bcachefs with recoverable data has been a pleasant experience. Compression, encryption, checksumming, deduplication, easy filesystem resizing, SSD acceleration, ease of adding devices… it's good to have it all in one place.