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Anirban Mondal
Effective
Dynamic Replication in Wide-Area Network Environments:
A Perspective
Abstract: The unprecedented growth of data at geographically
distributed locations coupled with tremendous improvement in
networking capabilities over the last decade strongly motivate the
need for efficient data management in wide-area network (WAN)
environments such as Peer-to-Peer (P2P) networks and GRIDs. In
particular, performance and data availability demands on data
management in WAN applications are now greater than ever before.
While replication has been traditionally used for maximizing data
availability as well as for reducing query response times, this paper
contends that replication schemes for traditional environments (e.g.,
clusters) do not adequately address the requirements of WAN
environments. Notably, issues such as heterogeneity (in terms of
processing capacity, bandwidth, available disk space for storing
replicas, variations in operating systems), lack of centralized
control, lack of global knowledge, distributed ownership and
scalability make replication in WAN environments significantly more
challenging than in the case of traditional domains. Additionally,
given that the demographics of the user population vary more for WAN
environments than for traditional smaller-sized networks, different
users can be expected to desire different levels of replica
consistency. Hence, trade-offs between the availability of fresh data
and the level of replica consistency desired by the users need to be
examined meticulously. Given that the problem of dynamic replication
is similar in many respects for different types of WAN environments,
this paper first discusses dynamic replication issues which typically
arise in WAN environments and introduces our previously proposed
solutions to these issues. Then I will present specific issues that
arise in case of two representative WAN environments, namely P2P
systems and GRIDs.
Finally, I will provide a perspective concerning the future of
dynamic replication in WAN environments in the real world.
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