1. A solid state storage subsystem, comprising: an array of non-volatile solid state memory; and a controller that provides access to the array of non-volatile solid state memory by executing commands received from a host system; wherein the controller is operative to store usage statistics reflective of a current wear level of the array of non-volatile solid state memory with one or more associated timestamps in an area of said array that is not accessible via non-vendor-specific commands, and to provide access, via at least one vendor-specific command, to at least one of (1) the usage statistics, including said timestamps, and (2) data values derived by the controller from examining usage statistics obtained from two or more time periods.