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CMSC 34702-1 Cluster Computing Basics
Junchen Jiang The University of Chicago October 8, 2018
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MapReduce: Simplified Data Processing on Large Clusters The Google File System Bigtable: A Distributed Storage System for Structured Data Cassandra - A Decentralized Structured Storage System
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Consistency, Availability, Partition Tolerance
x x Replica 1 Replica 2
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Consistency, Availability, Partition Tolerance
Any read must return the last written value set(y) y x Replica 1 Replica 2
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Consistency, Availability, Partition Tolerance
Any read must return the last written value set(y) y y Replica 1 Replica 2
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Consistency, Availability, Partition Tolerance
Any read must return the last written value set(y) y get() y y Replica 1 Replica 2
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Consistency, Availability, Partition Tolerance
Any read must return the last written value x get() Availability Every request must result in a response x x Replica 1 Replica 2
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Consistency, Availability, Partition Tolerance
Any read must return the last written value y get() Availability Every request must result in a response Partition Tolerance Network can lose any messages between servers y x Replica 1 Replica 2
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Cassandra: Gossip-based consensus protocol
Consistency Any read must return the last written value set(y) x get() Availability Every request must result in a response Partition Tolerance Network can lose any messages between servers
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Bigtable: Paxos-based consensus protocol (Chubby)
Consistency Any read must return the last written value set(y) Availability Every request must result in a response Chubby Master Chubby Slave Partition Tolerance Network can lose any messages between servers Chubby Slave Chubby Slave Service is unavailable until a quorum is reached
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Is it possible to achieve all three simultaneously?
Cassandra Bigtable Impossible Consistency Any read must return the last written value Availability Every request must result in a response Partition Tolerance Network can lose any messages between servers Unfortunately, No. (CAP Theorem) (Eric Brewer.
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This Class: Stream Processing
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