# MSSP: A Blockchain Sharding Protocol Based on Multi-Shard Storage
## 6 Experiment
### Reliability  
MSSP adopts a mechanism of sending update proofs to achieve data updates, thereby ensuring the consistency of cross-shard transactions. The mechanism updates the data by sending a proof of update to the nodes. After the node completes a data update, it can take three different actions: (1) return a proof to confirm the completion of the update; (2) not return any confirmation; or (3) return a proof of completion with a random probability \(p\), as discussed in Section 4.4. The following will explore the advantages and disadvantages of the probability \(P\) returning to update completion proof mechanism from the perspectives of latency and security, compared to the other two methods.  
Figure 12 illustrates the latency situation corresponding to three different update proof return strategies. It can be seen from the figure that the strategy of always returning proof results in the longest latency, while the strategy of not returning proof at all corresponds to the shortest latency. The latency for returning proof with a probability \(P\) falls between these two extremes. However, in a well-networked environment, the difference in latency among these three strategies is not significant, usually on a millisecond level or shorter. This is mainly because the completed update proof file has a small volume, and its transmission time is mainly affected by one-way network delay. Therefore, although there are differences in latency among these three strategies, overall, this difference is mainly influenced by network conditions.  
The advantage of the \(P\)-probability returning update completion proof mechanism over the other two mechanisms is as follows:  
1. Faulty node exclusion: by detecting whether nodes complete updates on time within a certain time range, faulty nodes can be effectively excluded, thereby improving the fault tolerance of the system.
2. Reducing the impact of malicious nodes: By introducing the mechanism of random return proof, nodes are allowed to decide whether to return proofs and the probability of returning proofs based on their performance within a certain time window. This flexibility and randomness can prevent malicious nodes from evading system monitoring through simple pattern recognition.
3. Saving communication overhead: Compared to requiring all nodes to return proofs, this approach can save communication overhead. Not all nodes need to return proofs after each update. Nodes can decide whether to return proofs based on a certain probability, thus reducing communication load.  
Figure 12: Comparison of latency in three ways of returning update completion proof under different numbers of shards.  
Enhancing auditability: The buffer records whether nodes have completed updates on time in recent rounds, providing a basis for system auditing. By analyzing the information provided by the buffer, potential abnormal behavior can be detected and addressed.  
In summary, compared with the other two mechanisms, the \(P\)-probability returning update completion proof mechanism has significant advantages that effectively address threats from faulty nodes and malicious behavior while enhancing system stability and reliability.