Patent ID: 7032087

Claim:
A method for maintaining a data structure associated with a non-volatile memory system, the data structure being arranged to store contents relating to usage of a plurality of physical blocks included in the non-volatile memory system, the method comprising: determining when it is appropriate to update the contents stored in the data structure; obtaining at least a first differential erase count from the data structure when it is determined that it is appropriate to update the contents stored in the data structure, the first differential erase count being a plurality of bits arranged to provide information relating to a number of times a first physical block of the plurality of physical blocks has been erased; determining a first actual erase count when it is determined that it is appropriate to update the contents stored in the data structure, the first actual erase count being associated with a second physical block of the plurality of physical blocks, wherein the first actual erase count is a plurality of bits arranged to provide a number of times the second physical block has been erased; and updating the first differential erase count when it is determined that it is appropriate to update the contents stored in the data structure, wherein updating the first differential erase count includes using the first actual erase count.