system 200 e g via the memory controller 202 searches the fmt 214 for an entry corresponding to the received logical address each of the entries in the fmt 214 indicates a physical location of identified memory failure events in the primary memory 210 a and the back up memory 210 b at block 406 the memory system 200 determines whether an entry corresponding to the received logical address is found in the fmt 214 if not this means that no memory failure events were detected at the physical address of the target data in either the primary memory 210 a or the back up memory 210 b in this instance the read request is directed to the primary memory 210 a for retrieving the target data at block 408 alternatively the read request may be directed to one of the memories 210 a or 210 b based on a default function however if no entry corresponding to the received logical address is found in the fmt 214 at block 406 this means that a memory failure event has been identified for the respective physical address of the target data in this instance the memory system 200 handles the read request based on the contents of the fmt table 214 in an embodiment criteria may be established for determining which of the primary memory 210 a and the back up memory 210 b to use for directing read requests the criteria may be based on the type or severity of memory failure event identified chip mark.