Partially Eager Update Propagation and Freshness-Based Read Relaxation for Replicated Internet Services

Ho-Joong KIM  Seungryoul MAENG  

IEICE TRANSACTIONS on Information and Systems   Vol.E92-D   No.10   pp.1986-1998
Publication Date: 2009/10/01
Online ISSN: 1745-1361
DOI: 10.1587/transinf.E92.D.1986
Print ISSN: 0916-8532
Type of Manuscript: Special Section PAPER (Special Section on New Technologies and their Applications of the Internet)
Category: Parallel and Distributed Architecture
distributed system,  edge service,  data replication,  freshness,  consistency,  

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We propose an Edge-write architecture which performs eager update propagation for update requests for the corresponding secondary server, whereas it lazily propagates updates from other secondary servers. Our architecture resolves consistency problems caused by read/update decoupling in the conventional lazy update propagation-based system. It also improves overall scalability by alleviating the performance bottleneck at the primary server in compensation for increased but bounded response time. Such relaxed consistency management enables a read request to choose whether to read the replicated data immediately or to refresh it. We use the age of a local data copy as the freshness factor so that a secondary server can make a decision for freshness control independently. As a result, our freshness-controlled edge-write architecture benefits by adjusting a tradeoff between the response time and the correctness of data.