E. Anderson

Publications (2)0 Total impact

• Source

  Available from: Mustafa Uysal

  Conference Proceeding: Efficient eventual consistency in Pahoehoe, an erasure-coded key-blob archive

  E. Anderson, Xiaozhou Li, A. Merchant, M.A. Shah, K. Smathers, J. Tucek, M. Uysal, J.J. Wylie
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  ABSTRACT: Cloud computing demands cheap, always-on, and reliable storage. We describe Pahoehoe, a key-value cloud storage system we designed to store large objects cost-effectively with high availability. Pahoehoe stores objects across multiple data centers and provides eventual consistency so to be available during network partitions. Pahoehoe uses erasure codes to store objects with high reliability at low cost. Its use of erasure codes distinguishes Pahoehoe from other cloud storage systems, and presents a challenge for efficiently providing eventual consistency. We describe Pahoehoe's put, get, and convergence protocols-convergence being the decentralized protocol that ensures eventual consistency. We use simulated executions of Pahoehoe to evaluate the efficiency of convergence, in terms of message count and message bytes sent, for failure-free and expected failure scenarios (e.g., partitions and server unavailability). We describe and evaluate optimizations to the naïve convergence protocol that reduce the cost of convergence in all scenarios.
  Dependable Systems and Networks (DSN), 2010 IEEE/IFIP International Conference on; 08/2010
• Conference Proceeding: Efficient tracing and performance analysis for large distributed systems

  E. Anderson, C. Hoover, Xiaozhou Li, J. Tucek
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  ABSTRACT: Distributed systems are notoriously difficult to implement and debug. One important tool for understanding the behavior of distributed systems is tracing. Unfortunately, effective tracing for modern distributed systems faces several challenges. First, many interesting behaviors in distributed systems only occur rarely, or at full production scale. Hence we need tracing mechanisms which impose minimal overhead, in order to allow always-on tracing of production instances. Second, for high-speed systems, messages can be delivered in significantly less time than the error of traditional time synchronization techniques such as network time protocol (NTP), necessitating time adjustment techniques with much higher precision. Third, distributed systems today may generate millions of events per second systemwide, resulting in traces consisting of billions of events. Such large traces can overwhelm existing trace analysis tools. These challenges make effective tracing difficult. We present techniques that address these three challenges. Our contributions include (1) a low-overhead tracing mechanism, which allows tracing of large systems without impacting their behavior or performance (0.14 ¿s/event), (2) a post hoc technique for producing highly accurate time synchronization across hosts (within 10/ts, compared to between 100 ¿s to 2 ms for NTP), and (3) incremental data processing techniques which facilitate analyzing traces containing billions of trace points on desktop systems. We have successfully applied these techniques to two distributed systems, a cooperative caching system and a distributed storage system, and from our experience, we believe our techniques are applicable to other distributed systems.
  Modeling, Analysis & Simulation of Computer and Telecommunication Systems, 2009. MASCOTS '09. IEEE International Symposium on; 10/2009