Computation and Storage in the Cloud

Appendix C

Method of Calculating λ Based on Users’ Extra Budget

For designing cost-effective storage strategies, we propose a simple and efficient method to calculate the proper value of λ, with which more data sets can be stored within users’ extra budget.

For a given DDG, we can calculate the minimum cost benchmark and further know the storage cost and computation cost in the benchmark, denoted as S and C. Then, we denote the users’ extra budget as ε%, which means users are willing to pay ε% more than the benchmark to store the data sets for less data access delay. We further assume in the new strategy that the storage cost is S′ and computation cost is C′. Hence in the ideal case, we have

(C.1)

Due to the ε% extra budget, more data sets can ...