PPT-CSE 486/586 Distributed Systems

Paxos 1 Steve Ko Computer Sciences and Engineering University at Buffalo Recap NFS Caching with writethrough policy at close Stateless server One power efficient design FAWN Embedded CPUs amp Flash . Security --- 2. Steve Ko. Computer Sciences and Engineering. University at Buffalo. Recap. Three . types of functions. Cryptographic hash, symmetric key crypto, asymmetric key . crypto. Cryptographic hash. Google Chubby Lock Service. Steve Ko. Computer Sciences and Engineering. University at Buffalo. Recap. Paxos. is a consensus algorithm.. Proposers?. Acceptors?. Learners?. A proposer always makes sure that,. Paxos. --- 2. Steve Ko. Computer Sciences and Engineering. University at Buffalo. Recap. Paxos. is a consensus algorithm.. It allows multiple acceptors accepting multiple proposals.. A proposer always makes sure that,. Replication --- 1. Steve Ko. Computer Sciences and Engineering. University at Buffalo. Recap: Concurrency Control. Extracting more concurrency. Non-exclusive locks. Two-version locking. Reducing the lock overhead. Consistency --- 3. Steve Ko. Computer Sciences and Engineering. University at Buffalo. Recap. Consistency. Linearizability. Sequential consistency. Chain replication. Primary-backup (passive) replication. Byzantine Fault Tolerance. Steve Ko. Computer Sciences and Engineering. University at Buffalo. CSE 486/586 . Administrivia. Project 3 out. Please, please start right away!. Deadline: 4/30 (Monday) @ 11:59PM. Gossiping. Steve Ko. Computer Sciences and Engineering. University at Buffalo. Recall: Passive Replication. Request Communication. : the request is issued to the primary RM and carries a unique request id.. Concurrency . Control --- 1. Steve Ko. Computer Sciences and Engineering. University at Buffalo. Recap: Transactions. Transactions?. Abstraction for . grouping multiple operations into one. Transaction primitives?. Gossiping. Steve Ko. Computer Sciences and Engineering. University at Buffalo. Recap. Consistency models. Linearizability. Sequential consistency. Causal consistency. Eventual consistency. Depending on application scenarios, one consistency model makes more sense that others.. Byzantine Fault Tolerance --- 1. Steve Ko. Computer Sciences and Engineering. University at Buffalo. Recap. Spanner. Geo-distributed database. Supports a relational data model with a SQL-like language. Reliable Multicast --- 2. Steve Ko. Computer Sciences and Engineering. University at Buffalo. Recap: Multicast. How do a group of processes communicate?. Multicast. One-to-many: “Local” broadcast within a group . Gossiping. Steve Ko. Computer Sciences and Engineering. University at Buffalo. Recap. Available copies replication?. Read and write . p. roceed with live replicas. Cannot achieve one-copy serialization itself. Case Study: Facebook f4. Steve Ko. Computer Sciences and Engineering. University at Buffalo. Recap. Engineering principle. Make the common case fast, and rare cases correct. Power law. Haystack. A design for warm photos. Paxos. --- 2. Steve Ko. Computer Sciences and Engineering. University at Buffalo. Recap. Paxos. is a consensus algorithm.. It allows multiple acceptors accepting multiple proposals.. A proposer always makes sure that,.