As I describe in my blog, lengthy I / O operations do not require a stream at all . Rather, they use naturally-asynchronous I / O, which does not require a stream.
Device drivers typically use DMA, and this allows the device to directly read / write from the systemโs main RAM..NET complements this approach with IOCP (I / O completion port), which is part of the thread pool, allowing one thread (or very few threads) single-domain waiting on a huge number of input-output operations.
, , , await. - - , IOCP, , ( ..), ASP.NET . - , .