Memory system and control method thereof

Abstract

A memory system includes a nonvolatile memory including blocks as data erase units, a measuring unit which measures an erase time at which data in each block is erased, a block controller having a block table which associates a state value indicating one of a free state and a used state with the erase time for each block, a detector which detects blocks in which rewrite has collectively occurred within a short period, a first selector which selects a free block having an old erase time as a first block, a second selector which selects a block in use having an old erase time as a second block, and a leveling unit which moves data in the second block to the first block if the first block is included in the blocks detected by the detector.

Dependencies are inferred from the claim text.