>>It is obvious to me that I am able to write "through the cache" on the server (as MS puts it) from a client machine using FILE_FLAG_WRITE_THROUGH (just like SQL Server does).
>
>No, not quite. SQL Server completely by-passes the API and deals with the BIOS. While it does require Windows NT, the file I/O portion isn't used.

Yes, quite.

All versions of SQL Server open the log and data files using the Win32 CreateFile function. The dwFlagsAndAttributes member includes the FILE_FLAG_WRITE_THROUGH option when opened by SQL Server.

Q234656

And what's "Windows NT" got to do with it ? I think we've moved a bit beyond that OS as of late.