Patent ID: 8918609
Filing Date: 2014-12-23
Classification: G06F

Abstract:
1. A storage apparatus being coupled to a host computer, comprising: a plurality of storage devices including a first storage device and a second storage device whose performance is higher than that of the first storage device; and a controller being configured to provide a virtual volume including a plurality of logical areas to the host computer; and allocate at least one of a plurality of storage areas in the plurality of storage devices to a logical area of the virtual volume after receiving a write request to the logical area of the virtual volume; wherein, the controller is configured to: execute a first determination, in response to receiving a read request or a write request to the virtual volume, as to whether or not to migrate data in a first storage area of the first storage device allocated to a first logical area in the first virtual volume corresponding to the read request or the write request, to a second storage area of the second storage device based on an access frequency corresponding to the data of the first logical area; migrate the data in the first storage area of the first storage device to the second storage area of the second storage device according to a result of the determination; and allocate the second storage area of the second storage device to the first logical area in the virtual volume if the data in the first storage area is migrated based on the result of the first determination, wherein when a capacity of storage areas, for storing data migrated from the first storage area of the first storage device, in the second storage device is less than a threshold, the controller is configured to: execute a second determination as to whether or not to migrate data in a third storage area of the second storage device, which is allocated to a second logical area in the first virtual volume, to the first storage device according to an access frequency corresponding to the data of the second logical area; migrate the data in the third storage area of the second storage device to a fourth storage area of the first storage device based on a result of the second determination; and allocate the fourth storage area of the first storage device to the second logical area in the virtual volume if the data in the third storage area is migrated based on the result of the second determination.