Abstract: A system and method of avoiding preservation of files deleted in a flash memory by indicating deletion in a File Indication Map without modifying an associated block allocation map controls transfer of files from a full flash memory erase unit to a transfer flash memory erase unit. Modified File Indication Maps are compared with prior File Indication Maps to establish file deletion and to control modification of an associated block allocation map. The prior File Indication Map in flash memory is updated after comparison is completed.

Abstract: A system and method of cleaning up a full erase unit in a flash translation layer, including moving all valid blocks on the full erase unit to a corresponding address location on a predetermined transfer unit, and then erasing the contents of the full erase unit. After erasure, the formerly full erase unit is redesignated to become the next transfer unit to which the contents of the next full unit will be transferred. The method also includes determining whether a criterion has been met for cleanup to be undertaken. The criteria for undertaking cleanup includes determining whether the number of free blocks is greater than a threshold which is a function of twice the number of bad blocks in the transfer erase unit plus twice the number of flash translation layer structure blocks in the full erase unit.