Patent ID: 8141095

Claim:
A non-transitory computer-readable recording medium storing a data allocation control program executed by a computer, the data allocation control program managing data allocation when data is distributively stored in a plurality of disk nodes which are shifted to a power saving mode if no access is performed at a certain time, the program comprising: an access statistical information collecting step of collecting access statistical information representing the number of accesses performed to respective data managed by the disk nodes within a given time slot, from an access statistical information storage unit which stores the access statistical information; a no-access probability calculating step of referring to the access statistical information and setting, as a no-access-to-data probability for each data, a value that is increased for data with a smaller number of accesses within the given time slot; an allocation pattern candidate producing step of producing a plurality of allocation pattern candidates each indicating the disk nodes in which the respective data are to be stored; an expectation calculating step of calculating, for each of the produced allocation pattern candidates, the no-access-to-data probabilities for the respective data allocated in each of the disk nodes when the respective data are allocated according to the allocation pattern candidate, to thereby calculate a no-access-to-node probability representing a probability that access is not performed to each disk node, and tallying the respective no-access-to-node probabilities for the disk nodes, thus obtaining a no-access period expectation that represents an expected value of occurrence of a no-access period during which access is not performed to some of the disk nodes; an allocation pattern deciding step of selecting, as an allocation pattern for data reallocation, one of the plurality of produced allocation pattern candidates with the largest one of the calculated no-access period expectation; and a data reallocation instructing step of instructing the disk nodes to reallocate the respective data in accordance with the selected allocation pattern.