Yes it does lie especially with fsync() because that call's purpose was to flush all caches to disk, which is an expensive operation. Since then NCQ/TCQ were a

Yes it does lie especially with fsync() because that call's purpose was to flush all caches to disk, which is an expensive operation. Since then NCQ/TCQ were added to disks and also systems like Linux implemented write barriers to enable more control[1]. [1] https://monolight.cc/2011/06/barriers-caches-filesystems/ https://monolight.cc/2011/06/barriers-caches-filesystems/