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Auflistung nach Schlagwort "Non-volatile memory"

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  • Zeitschriftenartikel
    Designing an Event Store for a Modern Three-layer Storage Hierarchy
    (Datenbank-Spektrum: Vol. 20, No. 3, 2020) Glombiewski, Nikolaus; Götze, Philipp; Körber, Michael; Morgen, Andreas; Seeger, Bernhard
    Event stores face the difficult challenge of continuously ingesting massive temporal data streams while satisfying demanding query and recovery requirements. Many of today’s systems deal with multiple hardware-based trade-offs. For instance, long-term storage solutions balance keeping data in cheap secondary media (SSDs, HDDs) and performance-oriented main-memory caches. As an alternative, in-memory systems focus on performance, while sacrificing monetary costs, and, to some degree, recovery guarantees. The advent of persistent memory (PMem) led to a multitude of novel research proposals aiming to alleviate those trade-offs in various fields. So far, however, there is no proposal for a PMem-powered specialized event store. Based on ChronicleDB, we will present several complementary approaches for a three-layer architecture featuring main memory, PMem, and secondary storage. We enhance some of ChronicleDB’s components with PMem for better insertion and query performance as well as better recovery guarantees. At the same time, the three-layer architecture aims to keep the overall dollar cost of a system low. The limitations and opportunities of a PMem-enhanced event store serve as important groundwork for comprehensive system design exploiting a modern storage hierarchy.
  • Zeitschriftenartikel
    Towards Log-Less, Fine-Granular State Machine Replication
    (Datenbank-Spektrum: Vol. 20, No. 3, 2020) Skrzypzcak, Jan; Schintke, Florian
    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.