STORAGE APPARATUS WITH A PLURALITY OF NONVOLATILE MEMORY DEVICES

According to one embodiment, a counter counts bits having a predetermined logical value contained in accessed data to be written or read in an access process of accessing any of the physical blocks provided in a selected one of the nonvolatile memory devices. A timer measures an access busy period in the access process. A control module updates an access busy period data item stored in a busy period storage module and concerning the selected one, in accordance with a count value of the counter, whereby the access busy period data item represents the access busy period measured.