By default, Windows caches file data that is read from disks and written to disks. [..] Caching is managed per file object. The policy of delaying the writing of the data to the file and holding it in the cache until the cache is flushed is called lazy writing, and it is triggered by the cache manager at a determinate time interval. [..] The time at which a block of file data is flushed is partially based on the amount of time it has been stored in the cache and the amount of time since the data was last accessed in a read operation.
My question is how long does it take Windows to "really" write a file on disk?