1. A data storage device comprising: a memory configured to store data entries; a first input port; and a controller configured to: receive a first data entry over the first input port; store the first data entry in a first data structure in the memory; in connection with the storage of the first entry in the first data structure, store a second data entry corresponding to the first data entry in a second data structure separate from the first data structure, wherein entries of the second data structure include a valid bit field and one or more condition fields; and indicate, using the valid bit field of the second data entry in the second data structure, that the first data entry in the first data structure is valid.