Storage device calculating optimal read voltage using degradation information

A storage device comprising:

• a first memory device configured to store data requested by a host;
• a second memory device configured to store first degradation information of the first memory device in page units;
• and
• a controller configured to perform a first read operation on the first memory device using a first read voltage, and to acquire the first degradation information,
• wherein the second memory device estimates second degradation information of the first memory device based on the first degradation information, and calculates a second read voltage, used to perform a second read operation on the first memory device according to a request of the host, based on the second degradation information,
• wherein the controller is configured to change an amount of the number of error bits used to calculate the second degradation information, based on a possibility of occurrence of uncorrectable error correction code (UECC) existing in a target page in which the second read operation is performed, among the plurality of pages such that when a first possibility of occurrence of UECC is greater than a second possibility of occurrence of UECC, a larger number of errors bits is used to calculate the second degradation information for the first possibility of occurrence of UECC compared to the second possibility of occurrence of UECC.

A storage device comprising:

• a first memory device configured to store data requested by a host;
• a second memory device configured to store first degradation information of the first memory device;
• and
• a controller configured to detect the number of error bits generated by a first read operation on the first memory device as the first degradation information,
• wherein the first memory device estimates second degradation information of the first memory device, based on the first degradation information, in response to a request of a second read operation from the host, and uses a read voltage calculated based on the second degradation information to perform the second read operation, and
• a program unit of the second memory device is different from a program unit of the first memory device,
• wherein the second degradation information comprises results of comparing the number of error bits for a target page with a predetermined threshold value,
• wherein the first memory device uses the numbers of error bits at least one time stored in the second memory device to estimate the number of error bits generated by the second read operation, based on the results.