The storage controller 10 manages a recording area of the memory 16 based on a unit referred to as extent 40. The extent 40 is made to correspond to the user data block 32 and to the SSD block 21. Specifically, the extent 40 includes a plurality of stripe rows 41 each of which is a data unit for storage of data into a plurality of SSDs 20 in a distributed state. The stripe rows 41 each include a plurality of entries 42 that are made to correspond to the SSD blocks 21. The entries 42 each have any of a data area for recording the user data, a parity area for recording the redundant data, and a spare area to be reserved as a spare, as an attribute, in accordance with the RAID configuration of the parity group PG.

For storing the user data in the storage device 1, the host device 2 transmits the write request for the virtual volume 30 provided from the storage controller 10, to the storage device 1. The write request indicates the user data to be stored in the storage device 1 and information regarding location in the virtual volume 30 into which the user data is to be written.

Upon reception at the host I/F 11 of the write request from the host device 2, the storage controller 10 records the user data indicated by the write request, in the extent 40 linked to the user data block 32 corresponding to a virtual address. Specifically, the storage controller 10 records the user data in the recordable manner in the entries 42 which are included in each stripe row 41 in the extent 40 and of which the attribute is the data area.