Acne lesions, whether of inflammatory andor non-inflammatory type, are simultaneously or sequentially treated and their number reduced, via daily topical regimen, with the combination or association of adapalene or pharmaceutically acceptable salt thereof and benzoyl peroxide. An inverter timing system is connected to the power loss sensing device. When a host writes to an empty VV region, a logical disk region is allocated to the empty VV region so the formerly empty VV region becomes a filled VV region mapped to the allocated LD region. A flow-rate detector detects the flow rate of the processing solution supplied from each processing-solution supplier. The processor determines, when receiving an access request for a copy destination volume, presencenon-presence of a copy of a logical address for which the access request is made by using information in the first storing unit, and to access a physical address of the copy destination volume acquired from the second storing unit for a generation designated by a result of the determination.