[eps]

Write flushing is not a good example.

You still need FlushFileBuffers even with IOCP if files are opened in buffered mode (which is the default). While you will know when a write was completed, an explicit flush is still needed to make sure it’s written through. So it’s pretty much exactly the same case as with fsync(). Alternatively, you can use the write-through mode, but that kills performance like that, especially with a random write pattern.

IOCP is basically a better/cleaner abstracted epoll() that also doubles as a manager of a worker thread pool.