Storage control device, non-transitory computer-readable storage medium, and storage control method

A non-transitory computer-readable storage medium storing a program that causes a processor included in a storage control device to execute a process, the process comprising:

• when a first write request for writing first data to a first unit region among unit regions included in a first storage region is received, writing the first data to the first unit region in a second storage region corresponding to a snapshot, the snapshot being corresponding to the first storage region;
• sending a first completion response to the first write request for writing;
• when a first read request requesting for reading from the first unit region in the second storage region is received, sending second data stored in the first unit region in the first storage region, as read data in accordance with the first read request,
• writing, when a second write request for writing third data to the first unit region in the first storage region is received after a request for creating a following-generation snapshot corresponding to the first storage region is received, the third data to the first unit region in a third storage region corresponding to the following-generation snapshot;
• sending a second completion response to the second write request for writing the third data;
• sending, when a third read request requesting for reading from the first unit region in the third storage region is received, the second data stored in the first unit region in the first storage region, as read data in accordance with the third read request;
• and
• sending, when a fourth read request requesting for reading from the first unit region in the first storage region is received, the third data stored in the first unit region in the third storage region, as read data in accordance with the fourth read request.

A storage control method comprising:

• when a first write request for writing first data to a first unit region among unit regions included in a first storage region is received, writing the first data to the first unit region in a second storage region corresponding to a snapshot, the snapshot being corresponding to the first storage region;
• sending a first completion response to the first write request for writing;
• when a first read request requesting for reading from the first unit region in the second storage region is received, sending second data stored in the first unit region in the first storage region, as read data in accordance with the first read request,
• writing, when a second write request for writing third data to the first unit region in the first storage region is received after a request for creating a following-generation snapshot corresponding to the first storage region is received, the third data to the first unit region in a third storage region corresponding to the following-generation snapshot;
• sending a second completion response to the second write request for writing the third data;
• sending, when a third read request requesting for reading from the first unit region in the third storage region is received, the second data stored in the first unit region in the first storage region, as read data in accordance with the third read request;
• and
• sending, when a fourth read request requesting for reading from the first unit region in the first storage region is received, the third data stored in the first unit region in the third storage region, as read data in accordance with the fourth read request.