RMWPaxos: Fault-Tolerant In-Place Consensus Sequences

Skrzypczak, Jan; Schintke, Florian; Schütt, Thorsten

doi:10.1109/tpds.2020.2981891

Cited by 10 publications

(8 citation statements)

References 34 publications

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“…Mencius [49], Derecho [26], AllConcur [56] CP [36], RMW-Paxos [59], CASPaxos [58] Gryff [9], Generalized Paxos [37], EPaxos [51], Atlas [14], All-aboard Paxos [23] ABD [48], Hermes [33] Table 1: Taxonomy (implemented protocols are in bold) explaining how each protocol performs a read and a write to keys stored in the replicated KVS.…”

Section: Decentralized (Leaderless)mentioning

confidence: 99%

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Odyssey

Gavrielatos

Katsarakis

Nagarajan

2021

Proceedings of the Sixteenth European Conference on Computer Systems

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Get/Put Key-Value Stores (KVSes) rely on replication protocols to enforce consistency and guarantee availability. Today's modern hardware, with manycore servers and RDMAcapable networks, challenges the conventional wisdom on protocol design. In this paper, we investigate the impact of modern hardware on the performance of strongly-consistent replication protocols.First, we create an informal taxonomy of replication protocols, based on which we carefully select 10 protocols for analysis. Secondly, we present Odyssey, a framework tailored towards protocol implementation for multi-threaded, RDMA-enabled, in-memory, replicated KVSes. We implement all 10 protocols over Odyssey, and perform the first apples-to-apples comparison of replication protocols over modern hardware.Our comparison characterizes the protocol design space, revealing the performance capabilities of different classes of protocols on modern hardware. Among other things, our results demonstrate that some of the protocols that were efficient in yesterday's hardware are not so today because they cannot take advantage of the abundant parallelism and fast networking present in modern hardware. Conversely, some protocols that were inefficient in yesterday's hardware are very attractive today. We distill our findings in a concise set of general guidelines and recommendations for protocol selection and design in the era of modern hardware.

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Section: Decentralized (Leaderless)mentioning

confidence: 99%

“…Traditionally, CP has been regarded simply as a way to perform leader election so that Multi-Paxos can start executing. However, recent proposals [20,58,59] have used CP to reach consensus on which node should be the next to perform a write at a per key basis.…”

Section: Decentralized Per-key Order (Dpko)mentioning

confidence: 99%

Odyssey

Gavrielatos

Katsarakis

Nagarajan

2021

Proceedings of the Sixteenth European Conference on Computer Systems

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“…To avoid the need to clean-up old instances, we extended single-decree Paxos so that a single Paxos instance can agree on an arbitrarily long sequence of values. We call this modified protocol RMWPaxos [15], as it supports the consistent application of arbitrary read-modify-write operations on a single value. Informally, the protocol supports the following semantics (see [15] for a formal problem statement):…”

Section: Rmwpaxos: Enhancing Paxos With Consistent Quorumsmentioning

confidence: 99%

“…Scalaris features the architecture outlined in Section 5. A detailed evaluation can be found in [15].…”

Section: Deployment In a Distributed Kv-storementioning

confidence: 99%

Towards Log-Less, Fine-Granular State Machine Replication

Skrzypzcak

Schintke

2020

Datenbank Spektrum

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State machine replication is used to increase the availability of a service such as a data management system while ensuring consistent access to it. State-of-the-art implementations are based on a command log to gain linear write access to storage and avoid repeated transmissions of large replicas. However, the command log requires non-trivial state management such as allocation and pruning to prevent unbounded growth. By introducing in-place replicated state machines that do not use command logs, the log overhead can be avoided. Instead, replicas agree on a sequence of states, and former states are directly overwritten. This method enables the consistent, fault-tolerant replication of basic data management primitives such as counters, sets, or individual locks with little to no overhead. It matches the properties of fast, byte-addressable, non-volatile memory particularly well, where it is no longer necessary to rely on sequential access for good performance. Our approach is especially well suited for small states and fine-granular distributed data management as it occurs in key-value stores, for example.

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“…Thus a constant size redo log suffices for all operations. We neither allocate nor de-allocate memory for operations as all updates are in-place [54]. It shows its strengths for complex data structures where updates are global operations and touch large parts of the data structure.…”

Section: Introductionmentioning

confidence: 99%

Transactions on Red-black and AVL trees in NVRAM

Schütt¹,

Schintke²,

Skrzypczak³

2020

Preprint

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Byte-addressable non-volatile memory (NVRAM) supports persistent storage with low latency and high bandwidth. Complex data structures in it ought to be updated transactionally, so that they remain recoverable at all times. Traditional database technologies such as keeping a separate log, a journal, or shadow data work on a coarse-grained level, where the whole transaction is made visible using a final atomic update operation. These methods typically need significant additional space overhead and induce non-trivial overhead for log pruning, state maintenance, and resource (de-)allocation. Thus, they are not necessarily the best choice for NVRAM, which supports fine-grained, byte-addressable access.We present a generic transaction mechanism to update dynamic complex data structures 'in-place' with a constant memory overhead. It is independent of the size of the data structure. We demonstrate and evaluate our approach on Red-Black Trees and AVL Trees with a redo log of constant size (4 resp. 2 cache lines). The redo log guarantees that each accepted (started) transaction is executed eventually despite arbitrary many system crashes and recoveries in the meantime. We update complex data structures in local and remote NVRAM providing exactly once semantics and durable linearizability for multi-reader single-writer access. To persist data, we use the available processor instructions for NVRAM in the local case and remote direct memory access (RDMA) combined with a software agent in the remote case.

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RMWPaxos: Fault-Tolerant In-Place Consensus Sequences

Cited by 10 publications

References 34 publications

Odyssey

Odyssey

Towards Log-Less, Fine-Granular State Machine Replication

Transactions on Red-black and AVL trees in NVRAM

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