Patent ID: 8539194
Filing Date: 2013-09-17
Classification: G06F

Abstract:
1. A storage system, comprising: one or more physical storage devices including a plurality of physical storage areas; and a controller comprising a virtual volume including a plurality of first virtual areas to a host device, wherein the controller: wherein the management information includes: (2A) wherein when the capacity change command is for capacity increase, the processor: (2B) wherein when the capacity change command is for capacity reduction, the processor: wherein the virtual volume is a predetermined virtual storage space, wherein the management information includes storage space management information including a space capacity value indicating a capacity of the virtual storage space, wherein the virtual storage space includes another virtual volume, wherein the physical storage area management information is configured by a plurality of records, wherein the records correspond to an area configured by one or more of the virtual areas, and including a record ID and a physical storage area ID allocated to any of the virtual areas corresponding to the records, wherein in the process (2A-1), among an not-in-use record of the plurality of records configuring the physical storage area management information, the record corresponding to the virtual area corresponding to the first difference is selected as being associated with the virtual volume, wherein the volume management information includes, about the virtual volume and the other virtual volume, not only the capacity value but also a head address in the virtual storage space, an ID of the associated record, and a threshold ratio, wherein the processor makes a first determination whether or not the capacity increase is allowed by following the capacity increase command, and when a result of the first determination is negative, the processes (2A-1) to (2A-3) are not executed, and wherein the result of the first determination is positive when requirements of (3-1) to (3-4) are entirely satisfied, and is negative when the requirements thereof are not entirely satisfied, the requirements of (3-1) to (3-4) including: (3-1) the storage capacity following the capacity increase command is smaller in value than the space capacity value, (3-2) a head or end address of the virtual volume having the storage capacity following the capacity increase command is not falling in an address range of the other virtual volume specified by a head address and the capacity value in the volume information, (3-3) the number of the not-in-use records of the plurality of records configuring the physical storage area management information is equal to or larger than the number of the records corresponding to the virtual area of the first difference, and (3-4) in the virtual volume having the storage capacity following the capacity change command, a ratio of an entire capacity of the one or more virtual areas not allocated with any of the physical storage areas to an entire capacity of the one or more physical storage areas not allocated with any of the virtual areas is equal to or smaller than the threshold ratio of the virtual volume.