consistency

  • Reading Group. UniStore: A fault-tolerant marriage of causal and strong consistency

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    For the 80th paper in the reading group, we picked “UniStore: A fault-tolerant marriage of causal and strong consistency” by Manuel Bravo, Alexey Gotsman, Borja de Régil, and Hengfeng Wei. This ATC’21 paper adapts the Partial Order-Restrictions consistency (PoR) into a transactional model. UniStore uses PoR to reduce coordination efforts and execute as many transactions…

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  • Reading Group. Viewstamped Replication Revisited

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    Our 74th paper was a foundational one — we looked at Viestamped Replication protocol through the lens of the “Viewstamped Replication Revisited” paper. Joran Dirk Greef presented the protocol along with bits of his engineering experience using the protocol in practice. Viestamped Replication (VR) solves the problem of state machine replication in a crash fault…

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  • Reading Group. Strong and Efficient Consistency with Consistency-Aware Durability

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    In the 62nd reading group session, we covered the “Strong and Efficient Consistency with Consistency-Aware Durability” paper from FAST’20. Jesse did an excellent presentation for the group that explains the core of the paper rather well: This paper describes a problem with many leader-based replication protocols. It specifically focuses on ZooKeper and Zab, but similar…

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  • Reading Group. Conflict-free Replicated Data Types

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    We kicked off a new set of papers in the reading group with some fundamental reading – “Conflict-free Replicated Data Types.” Although not very old (and not the first one to suggest something similar to CRDTs), the paper we discussed presents a proper definition of Conflict-free Replicated Data Types (CRDTs) and the consistency framework around…

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  • Reading Group. New Directions in Cloud Programming

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    Recently we have discussed a CIDR’21 paper: “New Directions in Cloud Programming.” Murat Demirbas did the presentation: Quite honestly, I don’t like to write summaries for this kind of paper. Here, the authors propose a vision for the future of cloud applications, and I feel that summarizing a vision often results in the misinterpretation of…

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  • Reading Group. FlightTracker: Consistency across Read-Optimized Online Stores at Facebook

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    Last DistSys Reading Group we have discussed “FlightTracker: Consistency across Read-Optimized Online Stores at Facebook.” This paper is about consistency in Facebook’s TAO caching stack. TAO is a large social graph storage system composed of many caches, indexes, and persistent storage backends. The sheer size of Facebook and TAO makes it difficult to enforce meaningful…

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  • Reading Group. Pegasus: Tolerating Skewed Workloads in Distributed Storage with In-Network Coherence Directories

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    Hard to imagine, but the reading group just completed the 45th session. We discussed “Pegasus: Tolerating Skewed Workloads in Distributed Storage with In-Network Coherence Directories,” again from OSDI’20. Pegasus is one of these systems that are very obvious in the hindsight. However, this “obviousness” is deceptive — Dan Ports, one of the authors behind the…

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  • Reading Group. Cobra: Making Transactional Key-Value Stores Verifiably Serializable.

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    This Wednesday, we were talking about serializability checking of production databases. In particular, we looked at the recent OSDI’20 paper: “Cobra: Making Transactional Key-Value Stores Verifiably Serializable.” The paper explores the problem of verifying serializability in a black-box production system from a client point of view. This makes sense as serializability is an operational, client-observable…

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  • One Page Summary. Gryff: Unifying Consensus and Shared Registers

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    This paper by Matthew Burke, Audrey Cheng, and Wyatt Lloyd appeared in NSDI 2020 and explores an interesting idea of a hybrid replication protocol. The premise is very simple – we can take one protocol that solves a part of the problem well, and marry it with another protocol that excels at the second half…

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  • Paper Summary: Bolt-On Global Consistency for the Cloud

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    This paper appeared in SOCC 2018, but caught my Paxos attention only recently. The premise of the paper is to provide strong consistency in a heterogeneous storage system spanning multiple cloud providers and storage platforms. Going across cloud providers is challenging, since storage services at different clouds cannot directly talk to each other and replicate the…

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