Storage apparatus and data management method

Abstract

A storage apparatus for which a hierarchical data management system is adopted is designed so that when receiving a read request for a first logical area to which a first storage area of a first storage device in a virtual volume is allocated, whether or not to migrate data in a first storage area of the first storage device, to a storage area of a second storage device is decided according to an access frequency to the first logical area in synchronization with the read request. When it is decided that the data stored in the first storage area of the first storage device should be migrated to the storage area of the second storage device, the data is migrated to a second storage area of the second storage device and the second storage area thereof is allocated to the first logical area in the virtual volume.

1 . A storage apparatus 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 configured to:   provide a virtual volume including a plurality of logical areas to the host computer;   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;   after a first storage area is allocated to a first logical area in the virtual volume in response to a first write request to the first logical area of the virtual volume, upon receiving a read request or another write request to the first logical area of the virtual volume, execute a determination as to whether or not to migrate data in the first storage area of the first storage device 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.