Dynamic Reconfiguration: Abstraction and Optimal Asynchronous Solution

Providing clean and efficient foundations and tools for reconfiguration is a crucial enabler for distributed system management today. This work takes a step towards developing such foundations. It considers classic fault-tolerant atomic objects emulated on top of a static set of fault-prone servers, and turns them into dynamic ones. The specification of a dynamic object extends the corresponding static (non-dynamic) one with an API for changing the underlying set of fault-prone servers. Thus, in a dynamic model, an object can start in some configuration and continue in a different one. Its liveness is preserved through the reconfigurations it undergoes, tolerating a versatile set of faults as it shifts from one configuration to another. In this paper we present a general abstraction for asynchronous reconfiguration, and exemplify its usefulness for building two dynamic objects: a read/write register and a max-register. We first define a dynamic model with a clean failure condition that allows an administrator to reconfigure the system and switch off a server once the reconfiguration operation removing it completes. We then define the Reconfiguration abstraction and show how it can be used to build dynamic registers and max-registers. Finally, we give an optimal asynchronous algorithm implementing the Reconfiguration abstraction, which in turn leads to the first asynchronous (consensus-free) dynamic register emulation with optimal complexity. More concretely, faced with n requests for configuration changes, the number of configurations that the dynamic register is implemented over is n; and the complexity of each client operation is O(n)

Timed Quorum System for Large-Scale and Dynamic Environments

This paper presents Timed Quorum System (TQS), a new quorum system especially suited for large-scale and dynamic systems. TQS requires that two quorums intersect with high probability if they are used in the same small period of time. It proposed an algorithm that implements TQS and that verifies probabilistic atomicity: a consistency criterion that requires each operation to respect atomicity with high probability. This TQS implementation has quorum of size O(\sqrt{nD}) and expected access time of O(log \sqrt{nD}) message delays, where n measures the size of the system and D is a required parameter to handle dynamism

The Case for Reconfiguration without Consensus: Comparing Algorithms for Atomic Storage

We compare different algorithms for reconfigurable atomic storage in the data-centric model. We present the first experimental evaluation of two recently proposed algorithms for reconfiguration without consensus and compare them to established algorithms for reconfiguration both with and without consensus. Our evaluation reveals that the new algorithms offer a significant improvement in terms of latency and overhead for reconfiguration without consensus. Our evaluation also shows that reconfiguration without consensus, can obtain similar results to that of consensus-based reconfiguration, which relies on a stable leader. Moreover, the new algorithms also substantially reduces the overhead compared to consensus-based reconfiguration without a leader. While our analysis confirms our intuition that batching reconfiguration requests serves to reduce the overhead of reconfigurations, our evaluation also shows that it is equally important to separate reconfigurations from read and write operations. Specifically, we found that using read and write operations to assist in completing concurrent reconfigurations is in fact detrimental to the reconfiguration performance

Reconfigurable Distributed Storage for Dynamic Networks

This paper presents a new algorithm for implementing a reconfigurable distributed shared memory in an asynchronous dynamic network. The algorithm guarantees atomic consistency (linearizability) in all executions in the presence of arbitrary crash failures of the processing nodes, message delays, and message loss. The algorithm incorporates a classic quorum-based algorithm for read/write operations, and an optimized consensus protocol, based on Fast Paxos for reconfiguration, and achieves the design goals of: (i) allowing read and write operations to complete rapidly and (ii) providing long-term fault- tolerance through reconfiguration, a process that evolves the quorum configurations used by the read and write operations. The resulting algorithm tolerates dynamism. We formally prove our algorithm to be correct, we present its performance and compare it to existing reconfigurable memories, and we evaluate experimentally the cost of its reconfiguration mechanism

Reconfigurable Distributed Storage for Dynamic Networks

This paper presents a new algorithm for implementing a reconfigurable distributed shared memory in an asynchronous dynamic network. The algorithm guarantees atomic consistency (linearizability) in all executions in the presence of arbitrary crash failures of the processing nodes, message delays, and message loss. The algorithm incorporates a classic quorum-based algorithm for read/write operations, and an optimized consensus protocol, based on Fast Paxos for reconfiguration, and achieves the design goals of: (i) allowing read and write operations to complete rapidly and (ii) providing long-term fault tolerance through reconfiguration, a process that evolves the quorum configurations used by the read and write operations. The resulting algorithm tolerates dynamism. We formally prove our algorithm to be correct, we present its performance and compare it to existing reconfigurable memories, and we evaluate experimentally the cost of its reconfiguration mechanism

Reconfigurable Distributed Storage for Dynamic Networks

SETIYOWATI, RENNI INDAH.2020. Pengaruh Motivasi Kerja Dan Lingkungan Kerja Terhadap Kinerja Karyawan Pt Casuarina Harnessindo Kabupaten Pemalang.Skripsi. Pendidikan Ekonomi. Fakultas Keguruan Dan Ilmu Pendidikan. Universitas Pancasakti Tegal. Pembimbing I Dr. H. Faridah, M.Si Pembimbing II Dr. H. Basukiyatno, M.Pd Kata Kunci: Motivasi Kerja, Lingkungan Kerja, Kinerja Karyawan Penelitian ini bertujuan untuk mengetahui adanya (1) pengaruh motivasi kerja terhadap kinerja karyawan PT Casuarina Harnessindo Kabupaten Pemalang, (2) pengaruh lingkungan kerja terhadap kinerja karyawan PT Casuarina Harnessindo Kabupaten Pemalang, dan (3) pengaruh motivasi kerja dan lingkungan kerja terhadap kinerja karyawan PT Casuarina Harnessindo Kabupaten Pemalang. Penelitian ini menggunakan pendekatan kuantitatif. Jenis penelitian ini adalah korelasioan asosiatif. Populasi dalam penelitian ini adalah karyawan PT Casuarina Harnessindo pada bagian Quality. Metode pengumpulan data menggunakan metode observasi dan angket. Teknik analisi data yang digunakan adalah analisis deskripif, analisis regresi linier sederhana, dan analisis regresi linier beganda. Hasil penelitian menujukkan (1) motivasi kerja mempunyai pengaruh yang signifikan terhadap kinerja karyawan PT Casuarina Harnessindo Kabupaten Pemalang, (2) lingkungan kerja mempunyai pengaruh yang signifikan terhadap kinerja karyawan PT Casuarina Harnessindo Kabupaten Pemalang, dan (3) motivasi kerja dan lingkungan kerja secara bersama-sama mempunyai pengaruh yang signifikan terhadap kinerja karyawan PT Casuarina Harnessindo Kabupaten Pemalang. Berdasarkan hasil penelitian ini saran yang diberikan adalah Perusahaan agar lebih mempertahankan lingkungan kerja yang kondusif dengan menjaga lingkungan kerja fisik dan lingkungan kerja non fisik yang berhubunganya dengan fasilitas sarana dan prasarana, keselamatan kerja, peralatan dan hubungan antara sesama, sehingga dapat meningkatkan kinerja karyawan. Motivasi kerja dan lingkungan kerja bersama-sama berpengaruh signifikan terhadap kinerja karyawan PT Casuarina Harnessindo Kabupaten Pemalang. Hal ini dapat dilihat dari indikator kinerja antara lain: (1) kualitas hasil kerja; (2) efisiensi dalam tugas; (3) disiplin kerja; (4) inisiatif; (5) kehadiran; (6) kejujuran

Reconfigurable distributed storage for dynamic networks

Abstract. This paper presents a new algorithm, RDS (Reconfigurable Distributed Storage), for implementing a reconfigurable distributed shared memory in an asynchronous dynamic network. The algorithm guarantees atomic consistency (linearizability) in all executions in the presence of arbitrary crash failures of processors and message loss and delays. The algorithm incorporates a quorum-based read/write algorithm and an optimized consensus protocol, based on Paxos. RDS achieves the design goals of: (i) allowing read and write operations to complete rapidly, and (ii) providing long-term fault tolerance through reconfiguration, a process that evolves the quorum configurations used by the read and write operations. The new algorithm improves on previously developed alternatives by using a more efficient reconfiguration protocol, thus guaranteeing better fault tolerance and faster recovery from network instability. This paper presents RDS, a formal proof of correctness, conditional performance analysis, and experimental results