SafeFileHandle fr = CreateFile(soupath, GENERIC_READ, FILE_SHARE_READ, IntPtr.Zero, OPEN_EXISTING,FILE_FLAG_NO_BUFFERING, IntPtr.Zero);
            SafeFileHandle fw = CreateFile(destpath, GENERIC_WRITE, FILE_SHARE_READ, IntPtr.Zero, CREATE_ALWAYS,(FILE_FLAG_NO_BUFFERING | FILE_FLAG_WRITE_THROUGH), IntPtr.Zero);

            int bufferSize =1024* 1024 * 32;
            FileStream fsr = new FileStream(fr, FileAccess.Read);
            FileStream fsw = new FileStream(fw, FileAccess.Write);

            BinaryReader br = new BinaryReader(fsr);
            BinaryWriter bw = new BinaryWriter(fsw);
            byte[] buffer = new byte[bufferSize];
            Int64 len = fsr.Length;
            while (fsr.Position < fsr.Length)
            {
                int  readCount = br.Read(buffer, 0, bufferSize);
                bw.Write(buffer, 0, readCount);
            }
            br.Close();
            bw.Close();