Research And Implementation Of Wear Leveling Algorithm Based On Hybrid Mapping Scheme

With the development of information technology, data storage has become more andmore important in computer architecture. There is a new storage media: Flash. Theincreasing capacity, good I/O performance, good anti-interference performance and lowpower consumption make Solid-State disk (SSD) based on flash becoming the mainstreamof the next generation storage device instead of hard disk. But the life limits of flash willaffect the reliability of SSD. Along flash is widely used, the wear-leveling algorithm hasbeen proposed to solve this problem.Wear-leveling algorithm currently facing two problems:(1) Using the wear numberof physical block to distinguish the data update temperature, dose not truly reflect theactual data update frequency;(2) Garbage collection and wear-leveling mechanism willbring write amplification, and will make the I/O performance of flash gradually decline.To solve these problems, based on the study of several typical flash translation layerstructure and wear-leveling algorithm, this paper suggested solutions to the problemsrespectively:(1) A method to define data temperature. This method use heat factor whichis the physical block numbers distributed for logical block within a period of time tomeasure the temperature of the logical block data. Heat factor represents the demand levelof the logical block to physical block, thus more truly reflect the actual data updatefrequency;(2) A partition management wear-leveling algorithm. This algorithm usespartition management to make system always try to use copy_back way which have lessexpensive to migrate data when needed, and thus achieve the purpose of reducing theoverhead of data migration and accelerating the speed of data migration.Test result shows that the method based on heat factor has a high ability to identifydata update frequency, the partition management wear-leveling algorithm has greatlyimproved the data migration speed, and thus overcome the decline in I/O performancewhen SSD has been used for a period of time.