Distributed Storage System Study Guide

Distributed Storage System Study Guide

Glossary

Term DefinitionsBlockchainA distributed database maintained by participants to record transaction information and ensure data security and transparency.Distributed Storage System (DSS)A system that stores data on multiple nodes in a decentralized manner to improve data reliability and availability.HostA node that provides storage space and is responsible for storing and maintaining data.RenterA node that rents storage space and is responsible for uploading, downloading, and managing data.SentinelA node that is responsible for monitoring data integrity and performing data repair.Byzantine Fault Tolerance (BFT) refers to the ability of a system to operate normally and reach consensus in the presence of malicious or faulty nodes.Proof of Stake (PoS)A blockchain consensus mechanism that selects block producers based on the number of tokens held by the node and the time.Proof of Work (PoW)A blockchain consensus mechanism that requires nodes to perform complex calculations to compete for block production rights.Smart ContractA self-executing contract stored on the blockchain that defines the rights and obligations of both parties to a transaction.Merkle TreeA data structure used to efficiently verify the integrity of data. Sharding divides data into multiple parts and stores them on different nodes to improve data throughput and parallel processing capabilities. Short answer questions

What are the advantages of distributed storage systems (DSS) compared to traditional storage systems? (2-3 sentences)

Explain the difference between proof of stake (PoS) and proof of work (PoW), and explain why DSS chooses PoS. (2-3 sentences)

What role do smart contracts play in DSS systems? (2-3 sentences)

Describe the three phases of the PUT protocol and explain the purpose of each phase. (2-3 sentences)

How does the GET protocol ensure that the host returns the correct data to the tenant? (2-3 sentences)

Explain the role of the EXT protocol and how it works. (2-3 sentences)

What is the purpose of the PERM protocol and how does it achieve this purpose? (2-3 sentences)

How does the STOR protocol improve the security of data storage? (2-3 sentences)

Explain the role of the SEN protocol and the FIX protocol in data repair. (2-3 sentences)

What are the differences between the RETR protocol and the GET protocol? (2-3 sentences)

Answers to short questions

Distributed storage systems (DSS) have higher data reliability, availability, security, and transparency than traditional storage systems. DSS eliminates single points of failure by distributing data across multiple nodes, and ensures data security through encryption and consensus mechanisms.

PoS selects block producers based on the number of tokens held by the node and the time, while PoW requires nodes to perform complex calculations to compete for block production rights. DSS chooses PoS because it is more energy-efficient and environmentally friendly, and is more suitable for integrating devices of various sizes and computing power.

Smart contracts in the DSS system define, execute, and settle storage-related agreements. They are stored on the blockchain and maintained by all nodes to ensure the transparency and immutability of the contract.

The three phases of the PUT protocol are: finding potential hosts, negotiating contracts, and submitting proof of data upload. In the first phase, tenants look for hosts that meet their needs; in the second phase, tenants negotiate storage contract details with hosts; in the third phase, tenants upload data and submit proofs to ensure that the data has been successfully stored.

The GET protocol requires the host to submit the Merkle root of the data to the blockchain before returning the data. The tenant can verify the integrity of the data based on the Merkle root to ensure that the host returns the correct data.

The EXT protocol is used to extend the validity period of the storage contract. The tenant sends a renewal request to the host. If the host agrees, the two parties sign a new contract and submit it to the blockchain.

The PERM protocol allows tenants to authorize third parties to access their stored data. The tenant creates an access contract that specifies the third parties who can access the data and their permissions, and submits it to the blockchain.

The STOR protocol improves the security of data storage by sharding and storing the data on multiple hosts. Even if some hosts fail, tenants can still recover the complete data.

The SEN protocol defines the strategy for data repair, including the selection of sentinels, repair conditions, and budgets. The FIX protocol is executed by the sentinels to download data, generate new shards, and upload them to new hosts to restore the redundancy of the data.

The RETR protocol is used to retrieve data stored through the STOR protocol. Unlike the GET protocol, the RETR protocol needs to download data shards from multiple hosts, decrypt and reassemble them to obtain complete data.

Essay Questions

Discuss how DSS systems ensure data security and analyze the strengths and limitations of their security mechanisms.

Compare and contrast the PUT and GET protocols, focusing on how they achieve Byzantine fault tolerance and their impact on network scalability.

Analyze how the STOR protocol achieves data confidentiality and Byzantine fault tolerance recovery, and discuss its strengths and weaknesses.

Explain the roles and responsibilities of sentinels in a DSS system and evaluate their impact on the overall reliability of the system.

Discuss potential application scenarios for DSS systems and analyze the challenges and opportunities they may face in practical applications.