Patent ID: 7143262

Claim:
A storage allocation method for allocating a vacant storage region to a virtual volume from storage regions of at least one of storage devices when storage regions maintained by the storage devices are provided as virtualized volumes to a host computer, said method comprising: a first step of allocating a storage region for a required size to be allocated from said vacant storage region so that a remaining unallocated part of the required size to be allocated becomes smaller than a specified maximum region size of the vacant storage region; and a second step of, when said remaining unallocated part of said required size to be allocated becomes smaller than said specified maximum region size of the vacant storage region, acquiring a storage region having a size that is a smallest increment of the power of two that is not smaller than said remaining unallocated part of the required size from said vacant storage region for allocation; and a third step of, sorting the vacant storage region into a plurality of groups and dividing the virtual volume into a plurality of divisions for load dispersion among the plurality of divisions and dividing the required size to be allocated according to a specified number of divisions and assigning the divided required size to be allocated respectively to the plurality of groups for allocation.