1. A method, comprising: receiving, in a data storage device, a write data command to store data in a primary memory of the data storage device; storing the data in a buffer of the storage device; after storing the data in the buffer, issuing a command complete status indication indicating that the write data command has been completed; and after issuing the command complete status indication, storing the data in the primary memory of the storage device, wherein the primary memory comprises a first type of non-volatile memory, the buffer comprises a second type of non-volatile memory that is different from the first type of non-volatile memory.