Apple's custom NVMes are amazingly fast – if you don't care about data integrity
This F_FULLFSYNC behaviour has been like this on OSX for as long as I can remember. It is a hint to ensures that the data in the write buffer has been flushed to stable storage - this is historically a limitation of fsync that is being accounted for - are you 1000% sure it does as you expect on other OSes?<p>POSIX spec says no: <a href="https:&#x2F;&#x2F;pubs.opengroup.org&#x2F;onlinepubs&#x2F;9699919799&#x2F;functions&#x2F;fsync.html" rel="nofollow">https:&#x2F;&#x2F;pubs.opengroup.org&#x2F;onlinepubs&#x2F;9699919799&#x2F;functions&#x2F;f...</a><p>Maybe unrealistic expectation for all OSes to behave like linux.<p>Maybe linux fsync is more like F_BARRIERFSYNC than F_FULLFSYNC. You can retry with those for your benchmarks.<p>Also note that 3rd party drives are known to ignore F_FULLFSYNC, which is why there is an approved list of drives for mac pros. This could explain why you are seeing different figures if you are supplying F_FULLFSYNC in your benchmarks using those 3rd party drives.