a flash memory storage system with "no wear leveling" will not last very long if data is written to the flash. without wear leveling, the underlying flash controller must permanently assign the logical addresses from the operating system (os) to the physical addresses of the flash memory. this means that every write to a previously written block must first be read, erased, modified, and re-written to the same location. this approach is very time-consuming and frequently written locations will wear out quickly, while other locations will not be used at all. once a few blocks reach their end of life, such a device becomes inoperable.