FWIW this uncertainty in fsync behavior is essentially the cause of the recent PostgreSQL bug on ext4 (fixed in the last round of minor releases). Basically, o

FWIW this uncertainty in fsync behavior is essentially the cause of the recent PostgreSQL bug on ext4 (fixed in the last round of minor releases). Basically, on XFS and all other tested filesystems is seems to work just fine, on EXT4 we may loose the last rename() effects. So this makes it difficult to get the durability right, even when the project is as careful about it as PostgreSQL.