1. A method of recording data from a host comprising: (a) providing first and second nonvolatile storages, each for sequentially recording data units; (b) designating either the first or second storage as storage for priority information, said priority information allowing determination of whether a first data unit in the first storage was recorded before or after a second data unit in the second storage; (c) receiving the data from the host; (d) recording the received data to a next available location in either the first storage or the second storage respectively depending on whether or not a predetermined condition is satisfied; (e) wherein whenever the received data is being recorded to the designated storage, the priority information is also being recorded thereto; and (f) repeating (c)-(e) until there is no more received data to be recorded.