Operation of a Data Storage Device (DSD) including a Non-Volatile Semiconductor Memory (NVSM) and at least one disk. A size value is determined corresponding to a sequence of data to be read from or stored in the DSD. If the size value is less than a threshold value, the sequence of data is stored in the NVSM. If the size value is greater than the threshold value, a first portion of the sequence of data is stored in the NVSM and at least a remaining portion of the sequence of data is stored on the at least one disk. The threshold value is based on at least a preparation time for accessing data from the at least one disk and a throughput value of the NVSM for storing data in or retrieving data from the NVSM.