Redis-LinqPad

private ConnectionMultiplexer _connection;

void Main()
{
	_connection = ConnectionMultiplexer.Connect("localhost");
	
	var data = GetSessionData(GetKeys());
	
	data.Dump("Session State");
}
// Define other methods and classes here
private IEnumerable<RedisKey> GetKeys()
{
	var server = _connection.GetServer(_connection.GetEndPoints().First());
	return server.Keys(pattern: "*_Data");
}

private Dictionary<string, SessionInformation> GetSessionData(IEnumerable<RedisKey> keys)
{
	var db = _connection.GetDatabase();
	
	return keys.ToDictionary (k => k.ToString(), k => GetSessionState(db, k));
}

private class SessionInformation
{
	public Dictionary<string, object> Session {get; set; }
	public string Size {get;set;}
	public long SizeBytes {get;set;}
}

private SessionInformation GetSessionState(IDatabase db, string sessionKey)
{
	long size = 0;
	var session = db.HashGetAll(sessionKey).ToDictionary (entry => entry.Name.ToString(), entry => {
		byte[] raw = (byte[])entry.Value;
		size += raw.LongLength;
		return GetObjectFromBytes(raw);
	});
	
	return new SessionInformation { SizeBytes = size, Size = BytesToString(size), Session = session };
}

private static object GetObjectFromBytes(byte[] dataAsBytes)
{
  object obj;
  if (dataAsBytes == null)
  {
      return null;
  }
  BinaryFormatter binaryFormatter = new BinaryFormatter();
  using (MemoryStream memoryStream = new MemoryStream(dataAsBytes, 0, (int)dataAsBytes.Length))
  {
      memoryStream.Seek((long)0, SeekOrigin.Begin);
      object retObject = binaryFormatter.Deserialize(memoryStream);
	  obj = (retObject.GetType().Name != "RedisNull" ? retObject : null);
  }
  return obj;
}

private static string BytesToString(long byteCount)
{
    string[] suf = { "B", "KB", "MB", "GB", "TB", "PB", "EB" }; //Longs run out around EB
    if (byteCount == 0)
        return "0" + suf[0];
    long bytes = Math.Abs(byteCount);
    int place = Convert.ToInt32(Math.Floor(Math.Log(bytes, 1024)));
    double num = Math.Round(bytes / Math.Pow(1024, place), 1);
    return (Math.Sign(byteCount) * num).ToString() + suf[place];
}