1. In a computer device that uses flash memory to store data, a method comprising: maintaining one or more secondary data structures containing mappings of logical flash memory addresses to physical flash memory addresses, each secondary data structure having a predetermined capacity of mappings; maintaining one or more counters associated with each of the one or more secondary data structures, respectively, providing an indication of when each of the one or more secondary data structures reaches the predetermined capacity of mappings; and maintaining a master data structure containing a pointer to each of the one or more secondary data structures.