Given how many times btrfs has failed to read data or to mount (with an error), I would imagine this is why btrfs is used by Facebook: because it isn't afraid to 'just let it crash' (cleanly), to use Erlang rethoric.
Yeah, it's definitely true that you want a filesystem with data and metadata checksums if you want high reliability. (I think btrfs and ZFS are the only Linux-or-other-UNIX filesystems with data checksums?)
But I think the inference to make is that Facebook trusts btrfs to increase reliability, not that Facebook trusts their distributed systems to cover for btrfs decreasing reliability to gain performance (or features).
But I think the inference to make is that Facebook trusts btrfs to increase reliability, not that Facebook trusts their distributed systems to cover for btrfs decreasing reliability to gain performance (or features).