Memory controller, memory system with memory controller, and method of controlling flash memory

摘要

In the control of the number of program-erase cycles, physical blocks (PBs) are divided into plural groups on a basis of the number of program-erase cycles and a search for a free PB is performed in the groups when assigning a logical block (LB) to the free PB. In the search, a free PB among a group covering a small number of program-erase cycles precedes that among a group covering a large number of program-erase cycles. Further, when searching out a free PB in the search, data stored in a PB (source PB) included in a group covering a smaller number of program-erase cycles than that covered by a group including the free PB searched out are transferred to the free PB if there is the source PB. The source PB is a PB to which a LB is assigned earliest among a group including it.