STL MAPPING TABLE MANAGEMENT METHOD BASED ON ONDEMAND ALGORITHM

摘要

An STL mapping table management method based on an Ondemand algorithm. When a read operation is needed, a cache table LPT_stack is inquired by means of an LBA; if a corresponding mapping entry exists in the cache table, a corresponding PBA is obtained, and data is directly read after an actual physical block number is obtained by inquiring a BMT table; if no corresponding mapping item is found in a cache, all mapping entries in a sector where the mapping entry is located need to be put in the cache by looking up a mapping table in a disk. When a write operation is needed, an LBN where the LBA is located is calculated first, and a PBN is obtained by looking up a BMT table by using the LBN as an index; if no PBN exists, a data strip is directly allocated; otherwise, whether a corresponding data strip has a space for writing a data block is checked; if yes, direct writing is performed; otherwise, an erase operation is performed on the data strip to release invalid data blocks, and data is written into the corresponding strip; after the data is written, a corresponding mapping entry is modified.