Thesis Proposal

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Thesis Proposal

• Data Consistency in DHTs

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Background

• Peer-to-peer systems have become increasingly
  popular
• Lots of P2P applications around us
• File sharing, file storage, Real time
  broadcasting,
• Advantages of P2P system
• Scalable
• load balance,
• fault-tolerant,
• low-cost deployment
• Why is it so magic?

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Core of P2P

• Each peer is a server and a client
• DHT
• Every peer can find each other and cooperate
• A hashed ID maps to a peer or an object
• The object would be stored on the closest peer

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Usages of DHT

• Directory service
• Very little amount of information, such as URI,
  metadata,
• Dont need to modified
• Storage
• Data, such as files,
• Immutable, only for downloading and uploading
• What is the next?

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Mutable DHT

• Most of DHT are for immutable data
• Immutable
• Data wouldnt be modified
• Operations of DHT
• ping, search, publish
• Mutable
• Data would be modified
• Operations of DHT
• ping, search, publish, delete, modified

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What is the challenge?

• Churn
• Peer join, leave, fail randomly
• Replica
• Fault-tolerant
• Problem
• Object consistency
• Replicas are consistent on
• different nodes

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What is the challenge?

• Network dynamic
• Partial unreachability
• Problem
• Key consistency
• Only one node is the root
• of a key

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Related work

• Consensus system
• Primary data maintainer
• Clients modify the data on primary one
• Do consensus algorithm
• After data modified
• After churn happened
• Quorum system
• No primary one
• Clients try to lock every replica
• before modifying

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Related work

• Authorization
• Contact the original closest one
• Get Authorized token of the closer partition
• Be the root of the partition

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Questions

• Is key consistency really a big assumption on
  realistic environment?
• For what kind of churn and mutability, do we need
  a strong consistency mechanism?
• The importance of key and data consistency
  mechanisms
• If we can guarantee only one of them, than what
  is the result on different situations?

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Experimental Plan

• Create a realistic network environment for
  simulation
• Result of data consistency on different churn and
  mutability
• DHT without any mechanism
• DHT with key consistency mechanism
• DHT with data consistency mechanism
• DHT with key and data consistency mechanisms

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Network Environment for Simulation

• Partial unreachability
• Path outage probability of internet
• Path outage duration and inter-duration
• Distribution of Node up and down
• Statistics of real p2p network
• Topology
• Hierarchical topology (few depth of AS)
• BRITE

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References

• Non-Transitive Connectivity and DHTs
• Key consistency in DHTs
• Toward Fault-tolerant Atomic Data Access in
  Mutable Distributed Hash Tables
• Etna a Fault-tolerant Algorithm for Atomic
  Mutable DHT Data
• PaxonDHT Achieving Consensus in Distributed Hash
  Tables
• MUREX A Mutable Replica Control Scheme for
  Structured Peer-to-Peer Storage Systems
• A Practical Distributed Mutual Exclusion Protocol
  in Dynamic Peer-to-Peer Systems
• An Experimental Study of the Skype Peer-to-Peer
  VoIP System
• Actively Monitoring Peers in KAD
• An Analysis of Network Reachability Using BGP
  Data
• PlanetSeeer Internet Path Failure Monitoring and
  Characterization in Wide-Area services
• Quantifying the Effects of Routing dynamics on
  End-to-End Internet Path Failures

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Next!!

• Questions
• Nothing
• Key consistency
• Data consistency
• Key and data consistency
• Narrow down
• What my application like?
• The parameters would be?
• Why cant Others experiment and parameters I use?
• Why they are not realistic
• Simulate the same other and change parameters to
  mine
• Churn Distributions parameters
• Experimental plans!! (all details)