Lec16 - Implementation Issues Two techniques to implement...

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Computer Science Lecture 16, page CS677: Distributed OS Implementation Issues Two techniques to implement consistency models Primary-based protocols Assume a primary replica for each data item Primary responsible for coordinating all writes Replicated write protocols No primary is assumed for a data item Writes can take place at any replica 1 Computer Science Lecture 16, page CS677: Distributed OS Remote-Write Protocols Traditionally used in client-server systems 2
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Computer Science Lecture 16, page CS677: Distributed OS Remote-Write Protocols (2) Primary-backup protocol Allow local reads, sent writes to primary Block on write until all replicas are notified Implements sequential consistency 3 Computer Science Lecture 16, page CS677: Distributed OS Local-Write Protocols (1) Primary-based local-write protocol in which a single copy is migrated between processes. Limitation: need to track the primary for each data item 4
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Computer Science Lecture 16, page CS677: Distributed OS Local-Write Protocols (2) Primary-backup protocol in which the primary migrates to the process wanting to perform an update 5 Computer Science Lecture 16, page CS677: Distributed OS Replicated-write Protocols Relax the assumption of one primary No primary, any replica is allowed to update Consistency is more complex to achieve Quorum-based protocols Use voting to request/acquire permissions from replicas Consider a file replicated on
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This note was uploaded on 11/22/2011 for the course COMPSCI 677 taught by Professor Shenoy during the Spring '08 term at UMass (Amherst).

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Lec16 - Implementation Issues Two techniques to implement...

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