Controller and storage device

A storage device comprising:

• a memory including a plurality of storage blocks, each of the plurality of storage blocks including pages configured to store data, wherein the pages included in each of the plurality of storage blocks include a valid page to which valid data is written and a snapshot page that stores data corresponding to or associated with data in the valid page;
• and
• a controller in communication with the memory to access information in the memory on the valid page and the snapshot page and configured to i) generate a valid segment including valid address data indicating an address of the valid page and valid map information indicating a storage location of the valid segment, ii) manage the valid page based on the valid segment and the valid map information, iii) generate a snapshot segment including snapshot address data indicating an address of the snapshot page and snapshot map information indicating a storage location of the snapshot segment, and iv) manage the snapshot page based on the snapshot segment and the snapshot map information.