PPT-Paxos A Consensus Algorithm for

Fault Tolerant Replication CS 5204 Fall 2008 System Model Messages possible indefinite delay possible duplication or loss delivered messages not corrupted replicas client Replicas. Cheap Paxos a variant of the Paxos al gorithm guarantees liveness under the additional as sumption that the set of nonfaulty processors does not jump around too fast but uses only F 1 main pro cessors that actually execute the system and F auxiliar lastclcamacuk ABSTRACT The Paxos algorithm is famously dif64257cult to reason about and even more so to implement despite having been synonymous with dis tributed consensus for over a decade The recently proposed Raft protocol lays claim to being a n Ali Ghodsi. alig@cs.berkeley.edu. Replicated State Machine (RSM). Distributed Systems 101. Fault-tolerance. . (partial, byzantine, recovery,...). Concurrency. (ordering, asynchrony, timing,...). Generic. A Consensus Algorithm for . Fault Tolerant Replication. CS 5204 – Fall, 2008. System Model. Messages. possible indefinite delay. possible duplication or loss. delivered messages not corrupted. . . .. James C. Corbett et al . OSDI 2012. Presenter: Akshay Ravichandran. Outline. What is Spanner?. Why Spanner?. Implementation. External Consistency. Concurrency Control. Evaluation. Related Work. Future Work. When you can’t agree to disagree. Consensus. Why do applications need consensus?. What does it mean to have consensus?. Consensus = consistency. Assumptions. Processes can choose values. Run at arbitrary speeds. Cezara. . Drăgoi. , INRIA ENS CNRS. Thomas A. . Henzinger. , IST Austria. Damien Zufferey. , MIT CSAIL. SNAPL, 2015.05.04. Fault-tolerant distributed algorithms. How to get it right when things go wrong ?. Burcu Canakci & Matt Burke. . Outline. Consensus. The Part-Time Parliament. Single-Decree Paxos. Liveness. Multi-Decree Paxos. Paxos Variants. Conclusion. Outline. Consensus. The Part-Time Parliament. . Distributed. . Systems. Crash. . Fault. . Tolerance. Sisi. . Duan. Assistant. . Professor. Information. . Systems. sduan@umbc.edu. Outline. A. . brief. . history. . of. . consensus. Paxos. Consensus I FLP Impossibility, Paxos COS 418: Distributed Systems Lecture 7 Michael Freedman 2 Recall our 2PC commit problem C  TC: “go!” TC  A, B: “prepare!” A, B  P: “yes” Paxos and Replicated State Machine (RSM) Outline Basic Concepts of Replicated State Machine Paxos Made Simple Replicated State Machine We can replicate data, how can we guarantee it is correctly replicated? . Oct 22, 2018. What is consensus?. A group of people go to the same place for the same meal.. → A set of nodes have the same value for the same variable.. X=. 7. X=7. X=7. Why is it important?. In state machine replication (SMR):. Lecture 16. , Oct 22. nd. 2015 . How’d we get here?. Failures & single systems; fault tolerance techniques added redundancy (ECC memory, RAID, etc.). Conceptually, ECC & RAID both put a “master” in front of the redundancy to mask it from clients -- ECC handled by memory controller, RAID looks like a very reliable hard drive behind a (special) controller. AMB Review 11/2010. Consensus Clustering . (. Monti. et al. 2002). Internal validation method for clustering algorithms.. Stability based technique.. Can be used to compare algorithms or for estimating the number of clusters in the data..