GenerateFile

 private static void Generate100MbFile()
        {
            long size = 0;
            int counter = 0;
            Random rnd = new Random();
            Encoding encoding = Encoding.GetEncoding("UTF-8");
            string[] elements = new string[] { "Start ", "startt ", "Starter " }; // Create words for text file

            using (StreamWriter writeFile = new StreamWriter(@"..\..\File.txt", true, encoding))
            {
                Console.WriteLine("This file is generated, please wait ...");

                /* 104857600 => 100 Mb.*/
                while (size < 104857600)
                {
                    writeFile.Write(elements[rnd.Next(0, 3)]);

                    if (counter % 10 == 0)
                    {
                        writeFile.WriteLine();

                        /* optimize speed !*/
                        if (counter % 100 == 0)
                        {
                            FileInfo file = new FileInfo(@"..\..\File.txt");
                            size = file.Length; // Get current file size
                            writeFile.Flush(); // Write to Hard disk
                        }
                    }

                    counter++;
                }

                Console.WriteLine("Generate is done !!!");
            }
        }