write/read speed

Program.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Threading.Tasks;

namespace readmany
{
    class Program
    {
        static void Main(string[] args)
        {
            MainAsync(args).GetAwaiter().GetResult();
        }

        static async Task MainAsync(string[] args)
        {

            var data = new byte[1 << 20];
            var concurrency = 1;
            var times = 400;
            new Random().NextBytes(data);

            var tasks = new List<Task<double>>();
            var sw = new Stopwatch();
            sw.Start();

            for (var loop = 0; loop != concurrency; ++loop)
            {
                tasks.Add(DoWrites(data, times, loop));
            }

            double Mbit = 0;
            foreach (var task in tasks)
            {
                Mbit += await task;
            }

            sw.Stop();


            tasks.Clear();
            var sw2 = new Stopwatch();
            sw2.Start();

            for (var loop = 0; loop != concurrency; ++loop)
            {
                tasks.Add(DoReads(times, loop));
            }

            Mbit = 0;
            foreach (var task in tasks)
            {
                Mbit += await task;
            }

            sw2.Stop();

            Console.WriteLine($"Total Write {Mbit / sw.Elapsed.TotalSeconds:N3} Mbps");
            Console.WriteLine($"Total Read {Mbit / sw2.Elapsed.TotalSeconds:N3} Mbps");
        }

        private static async Task<double> DoWrites(byte[] data, int times, int loop)
        {
            await Task.Delay(1);

            var sw = new Stopwatch();
            using (var file = File.Create($@"z:\\data{loop}.dat"))
            {
                sw.Start();
                for (var count = 0; count != times; ++count)
                {
                    await file.WriteAsync(data, 0, data.Length);
                }
                file.Close();
                sw.Stop();
            }
            var MByte = (data.Length * times) * 1.0 / (1 << 20);
            var Mbit = MByte * 8;
            Console.WriteLine($"Write {Mbit / sw.Elapsed.TotalSeconds:N3} Mbps");
            return Mbit;
        }

        private static async Task<double> DoReads(int times, int loop)
        {
            await Task.Delay(1);

            var data = new byte[1 << 20];
            var total = 0;

            var sw = new Stopwatch();
            using (var file = File.OpenRead($@"z:\\data{loop}.dat"))
            {
                sw.Start();
                for (var count = 0; count != times; ++count)
                {
                    total += await file.ReadAsync(data, 0, data.Length);
                }
                if (total != data.Length * times)
                {
                    throw new Exception("Not enough data was read");
                }
                file.Close();
                sw.Stop();
            }
            var MByte = (data.Length * times) * 1.0 / (1 << 20);
            var Mbit = MByte * 8;
            Console.WriteLine($"Read {Mbit / sw.Elapsed.TotalSeconds:N3} Mbps");
            return Mbit;
        }
    }
}

writeread.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp3.0</TargetFramework>
  </PropertyGroup>

</Project>