public async void TestWriteAsync()
{
var bytes = new byte[9 * 1024];
int position = 0;
random.NextBytes(bytes);
blocks.Position = 0;
master.Position = 0;
while (position < bytes.Length)
{
int n = Math.Min(bytes.Length - position, random.Next() % 4096);
await blocks.WriteAsync(bytes, position, n);
await master.WriteAsync(bytes, position, n);
position += n;
}
await blocks.FlushAsync();
await master.FlushAsync();
}