Dynamic file migration in distributed computer systems
Communications of the ACM
Competitive algorithms for distributed data management (extended abstract)
STOC '92 Proceedings of the twenty-fourth annual ACM symposium on Theory of computing
Online computation and competitive analysis
Online computation and competitive analysis
Competitive On-Line Algorithms for Distributed Data Management
SIAM Journal on Computing
Wireless sensor networks: a survey
Computer Networks: The International Journal of Computer and Telecommunications Networking
Developments from a June 1996 seminar on Online algorithms: the state of the art
Provably Good and Practical Strategies for Non-Uniform Data Management in Networks
ESA '99 Proceedings of the 7th Annual European Symposium on Algorithms
Exploiting Locality for Data Management in Systems of Limited Bandwidth
FOCS '97 Proceedings of the 38th Annual Symposium on Foundations of Computer Science
Fighting against two adversaries: page migration in dynamic networks
Proceedings of the sixteenth annual ACM symposium on Parallelism in algorithms and architectures
Optimal algorithms for page migration in dynamic networks
Journal of Discrete Algorithms
Page migration in dynamic networks
MFCS'05 Proceedings of the 30th international conference on Mathematical Foundations of Computer Science
Improved algorithms for dynamic page migration
STACS'05 Proceedings of the 22nd annual conference on Theoretical Aspects of Computer Science
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This paper extends the online file allocation problem of Bartal et al. to the following scenario: An indivisible file consisting of multiple units is stored on a network of stationary servers which are connected to a mobile ad hoc network. We model the mobile ad hoc network as a dynamic unit disk graph. The mobile nodes access single units (read/write) of the file using multihop paths to a close-by server, if they do not posses a copy of the file. In order to minimize the amount of data to be transferred, the data management system may create/delete copies of the complete file on arbitrary mobile nodes. Our cost model addresses the overall power consumption of the nodes of the mobile ad hoc network needed for the data management. It consists of a time dependent stand-by power consumption of the mobile nodes and the power consumption used by the hops during data transfers between the servers and the mobile nodes. We introduce the notion of an "energy-distance" which is the energy consumed by a data transfer of an unit-sized message between a server and a mobile node. Our main focus lies on the online version of the problem. An online algorithm neither knows the dynamics of the mobile ad hoc network nor the requests of the nodes in advance. We give oblivious lower bounds of the competitive ratio for arbitrary randomized algorithms and for the natural class of demand-driven algorithms, i.e. algorithms which replicate only near nodes which recently accessed the file. Furthermore, we give two demand-driven algorithms. We measure the quality of these algorithms using a refinement of the competitive ratio which gives an amortized competitive ratio for every time step depending on the actual changes of the energy-distances of the nodes in this step.