PPT-Distributed Consensus Paxos

Ethan Cecchetti October 18 2016 CS6410 Some structure taken from Robert Burgesss 2009 slides on this topic State Machine Replication SMR View a server as a state machine To replicate the server. 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 Presenter-. Kurchi. . S. ubhra. . H. azra. Agenda. Basic Algorithms such as Leader Election. Consensus in Distributed Systems. Replication and Fault Tolerance in Distributed Systems. GFS as an example of a Distributed System. 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. . . .. Paxos. --- 1. Steve Ko. Computer Sciences and Engineering. University at Buffalo. Recap. NFS. Caching with write-through policy at close(). Stateless server. One power efficient design: FAWN. Embedded CPUs & Flash . Replication. 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. . Distributed. . Systems. Crash. . Fault. . Tolerance. Sisi. . Duan. Assistant. . Professor. Information. . Systems. sduan@umbc.edu. Outline. A. . brief. . history. . of. . consensus. Paxos. Lecture 11, . Oct 6. th. . 2016 . 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. 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):. Each 42the OI 2DSeuTli and zPage wIIPwC hwaccuracy Page wcash Seive trading Page won iiaiiOtiS urior Oii7i bligaiioris 1Page wPaxos Page wIn MIX32 bSPage wiv ZZ Page wParticipant vJii reyuird O c27gQ Paxos. COS 418: Distributed Systems. Lecture . 10. Wyatt Lloyd. Let different replicas assume role of primary over time. System moves through a sequence of views. How do the nodes agree on view / primary?. Byzantine Generals Problem. Solution with signed message. . A . signed message. satisfies all the conditions of oral message, plus . two extra conditions. Signature cannot be forged. Forged message are detected and discarded by loyal generals.. L. anguage . for . Fault-tolerant Distributed . A. lgorithms. Cezara. . Drăgoi. , INRIA ENS CNRS. Thomas A. . Henzinger. , IST Austria. Damien Zufferey. , MIT CSAIL. POPL, 2016.1.21. 1. Motivation.