1. Apparatus for the storage of digital data organized into records comprising: host interface means for receiving data from a host computer; cache means connected to said host interface means for temporary storage of said data; storage device interface means for connecting said cache means to one or more memory storage devices of one or more classes of storage devices for comparatively long-term storage of said data; ad controller means including address recall means, for: (a) determining where said data is to be stored on said one or more storage devices; (b) controlling flow of said data from said host interface means through said cache means and said storage device interface means onto said one or more storage devices; and (c) storing the addresses at which said data has been stored on said one or more storage devices; whereby a given user-defined data set may be stored on a plurality of storage devices, selected from one or more classes of storage devices by said controller means.