Researcher:
Güler, Berkin

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Master Student

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Berkin

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Güler

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Güler, Berkin

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2017 - 20186

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Researcher Of Publications: search.filters.isAuthorOfPublication.af40fa01-fa70-4ce8-8560-6a40d3a1bb77

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    Compressed incremental checkpointing for efficient replicated key-value stores
    (Institute of Electrical and Electronics Engineers (IEEE), 2017) N/A; Department of Computer Engineering; Güler, Berkin; Özkasap, Öznur; Master Student; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 113507
    The prominent cloud services rely on geographically distributed nodes running replication and other fault-tolerance mechanisms so as to provide flawless availability and dependability. In this paper, we address the communication cost of the well known primary-backup replication protocol, and propose compressed periodic incremental checkpoint algorithms to achieve improved throughput. We set up a replicated key-value store on geographically distributed nodes of the PlanetLab platform, and developed compressed incremental checkpointing algorithms to support primary-backup replication. By considering performance metrics of interest including blocking time, checkpointing time, compression ratio, compression/ decompression times, we conducted a comprehensive analysis. We used the well-known benchmarking tool YCSB and established different sample workloads to test where each workload represents diverse plots. Our findings indicate that Zstd is the most competent compression method under all scenarios and through comparing with an uncompressed approach we point out that compressing the communication data disseminated from the primary replica coupled with the periodic incremental checkpointing algorithm not only decreases the average blocking time up to 5% but it also improves the overall system throughput by 4% compared to the no compression case.
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    Efficient incremental checkpoint algorithm for primary-backup replication
    (IEEE, 2017) N/A; Department of Computer Engineering; Güler, Berkin; Özkasap, Öznur; Master Student; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 113507
    Replication protocols are widely used for enabling fault tolerance and reliability features in distributed systems aiming fast recovery and seamless transition. In this study, we propose an efficient incremental checkpoint algorithm for primary-backup replication protocols to increase the system throughput. We developed an in-memory key-value store configured by the primary-backup replication protocol and set it up on the geographically distributed nodes of the PlanetLab overlay network. We performed measurements for metrics of interest on both the client and the primary replica side. Our findings show that the proposed incremental checkpoint algorithm not. only assures 2-3 times lower average blocking times but also guarantees a near-steady minimum average blocking time.
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    Efficient checkpointing mechanisms for primary-backup replication on the cloud
    (Wiley, 2018) N/A; Department of Computer Engineering; Güler, Berkin; Özkasap, Öznur; Master Student; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 113507
    Several distributed services ranging from key-value stores to cloud storage require fault-tolerance and reliability features. For enabling fast recovery and seamless transition, primary-backup replication protocols are widely used in different application settings including distributed databases, web services, and the Internet of Things. In this study, we elaborate the ways of enhancing the efficiency of the primary-backup replication protocol by introducing various checkpointing techniques. We develop a geographically replicated key-value store based on the RocksDB and use the PlanetLab testbed network for large-scale performance analysis. Using various metrics of interest including blocking time, checkpointing time, checkpoint size, failover time, and throughput and testing with practical workloads via the YCSB tool, our findings indicate that periodic-incremental checkpointing promises up to 5 times decrease in blocking time and a drastic improvement on the overall throughput compared to the traditional primary-backup replication. Furthermore, enabling Snappy compression algorithm on the periodic-incremental checkpointing leads to further reduction in blocking time and increases system throughput compared to the traditional primary-backup replication.
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    Secure chain replication
    (Institute of Electrical and Electronics Engineers (IEEE), 2017) N/A; Department of Computer Engineering; Güler, Berkin; Özkasap, Öznur; Master Student; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 113507
    We propose an approach for enabling secure chain replication that is resilient against crash and arbitrary failures. The main contribution is provided by a service named Elias which acts as a proxy between clients and the chain replication system. Elias is a trusted service that ensures the secure communication between clients and the replication system while detecting any arbitrary failures through cryptographic hashing. Elias also provides reconfiguration for the chain to eliminate the node affected by a crash or arbitrary failure.
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    Efficient incremental checkpoint algorithm for primary-backup replication
    (Institute of Electrical and Electronics Engineers (IEEE), 2017) N/A; Department of Computer Engineering; Güler, Berkin; Özkasap, Öznur; Master Student; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 113507
    Replication protocols are widely used for enabling fault tolerance and reliability features in distributed systems aiming fast recovery and seamless transition. In this study, we propose an efficient incremental checkpoint algorithm for primary-backup replication protocols to increase the system throughput. We developed an in-memory key-value store configured by the primary-backup replication protocol and set it up on the geographically distributed nodes of the PlanetLab overlay network. We performed measurements for metrics of interest on both the client and the primary replica side. Our findings show that the proposed incremental checkpoint algorithm not only assures 2-3 times lower average blocking times but also guarantees a near-steady minimum average blocking time./ Öz: Replikasyon protokolleri özellikle hızlı iyileşme ve kesintisiz geçiş sunmayı amaçlayan dağıtık sistemlerde yaygın kullanılan ve hata dayanıklılığı ile güvenilirlik özellikleri katan tekniklerdir. Bu çalışmada, birincil-yedek replikasyon protokolü için sistem başarımını artırmaya yönelik etkin artımlı bir denetim noktası algoritması önermekteyiz. Geliştirdigimiz bellek-içi anahtar-değer veritabanı, birincil-yedek replikasyon protokolü ve artımlı denetim noktası algoritması PlanetLab gerçek ağ senar- yoları ve coğrafi olarak dağılmış düğümlerinde çalıştırılmıştır. Replikasyon düğümleri ve istemci tarafında başarım kriterlerinin ölçümleri yapılmıştır. Önerdiğimiz, sistem yükünü gözeterek di- namik periyot tabanlı artımlı denetim noktası algoritmasını statik periyot sunan algoritma ile karşılaştırdık. Yapılan ölçümlemeler, önerdiğimiz algoritmanın diğerlerine göre 2-3 kat daha az or- talama gecikme süresi sunabildiğini ve aynı zamanda minimum düzeyde sabit bir gecikme süresini koruyabildiğini göstermiştir.
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    Analysis of checkpointing algorithms for primary-backup replication
    (Institute of Electrical and Electronics Engineers (IEEE), 2017) N/A; Department of Computer Engineering; Güler, Berkin; Özkasap, Öznur; Master Student; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 113507
    Replication is useful for supporting fault-tolerance, reliable and recovery oriented distributed systems. Popular application areas include databases, P2P systems, web services and Internet of Things. In this study, we propose utilizing the checkpointing concept for improving the efficiency of the well-known primary-backup replication protocol in distributed systems. We developed a software framework based on an in-memory replicated key-value store to evaluate various checkpointing algorithms. Using the framework over geographically distributed nodes of the PlanetLab platform, we performed extensive experiments and analysis with several different metrics, including blocking time, checkpointing time, checkpoint size and recovery time. Experimental scenarios consist of using the well-known benchmarking tool, YCSB, performing realistic read/update queries through exemplary workloads. Our findings indicate that incremental checkpointing combined with a periodic usage is the most efficient approach with having up to 30-times better system throughput and 50% decrease in average blocking times compared to traditional primary-backup replication and other checkpointing algorithms.