FIG. 7 is a flowchart illustrating an operating method of the storage device of FIG. 1. Referring to FIGS. 1, and 5 to 7, in operation S110, a read command and a read address are received. For example, the read command and the read address may be provided from an external host device to the controller 120.

In operation S120, the controller 120 may count the number of read commands on each of the zones Zone_1a to Zone_4a of the selected memory block BLKz. For example, the controller 120 may manage a read count associated with each of the zones Zone_1a to Zone_4a.

In operation S130, the controller 120 may determine whether a read count associated at least one of the zones Zone_1a to Zone_4a reaches a threshold value. For example, if a zone of which the read count reaches the threshold value is absent, the reliability verification read operation need not be performed. If a zone of which the read count reaches the threshold value exists, in operation S140, the reliability verification read operation may be performed.

For example, if a read count of the first zone Zone_1a reaches the first threshold value N1, the controller 120 may perform the reliability verification read operation on the word lines WL1 and WL2 included in the first zone Zone_1a. As such, if a read count reaches a given threshold value of zone, the controller 120 may perform the reliability verification read operation on the zone.