1. A solid state storage subsystem, comprising: an array of non-volatile solid state memory; and data interface circuitry, comprising: a data connector configured to connect the storage subsystem to a host system, the data connector having a form factor accommodating a number of signal lines of a first standardized data transfer interface; a controller that: accesses the array of non-volatile solid state memory in response to commands received from the host system via a second standardized data transfer interface that has fewer signal lines than the first standardized data transfer interface, wherein a first subset of the signal lines of the data connector are used to implement the second standardized data transfer interface; and transmits user data from the array of non-volatile solid state memory to the host system through the second standardized data transfer interface; wherein the controller is configured to maintain monitor data of the array of non-volatile solid state memory; and a monitor data transmission engine configured to send the monitor data to the host system via a second subset of said signal lines of the same data connector, the second subset being distinct from the first subset.