Provided are an apparatus, system and method to determine whether to use a low or high read voltage. First level indications of write addresses, for locations in the non-volatile memory to which write requests have been directed, are included in a first level data structure. For a write address of the write addresses having a first level indication in the first level data structure, the first level indication of the write address is removed from the first level data structure and a second level indication for the write address is added to a second level data structure to free space in the first level data structure to indicate a further write address. A first voltage level is used to read data from read addresses mapping to one of the first and second level indications in the first and the second level data structures, respectively. A second voltage level is used to read data from read addresses that do not map to one of the first and the second level indications the first and second level data structures, respectively.