Patent ID: 7302523

Claim:
A system for electronic storage of data objects on a computer readable medium, the system comprising at least one designated foreground data storage device and a plurality of designated background data storage devices, the foreground and background data storage devices being connectable by way of at least one releasable connection, and an interface engine adapted to manage the transfer of data objects to and from the devices and also between the foreground device and at least one of the plurality of background devices when the foreground and said at least one of the plurality of background devices are connected to each other, and to generate a logical stack of all the data objects stored in the system, including an index list of identifiers relating to the data objects, the index list being visible from either the foreground or the at least one background device whether connected to another designated data storage device or not, wherein an interface application is adapted automatically to move at least a first data object from said at least one designated foreground data storage device to at least one of said designated background data storage devices when there is insufficient room to transfer a second data object to said at least one designated foreground data storage device, when it is required to copy said second data object to said at least one first designated foreground device, and wherein the interface application is further adapted automatically to manage a chain of said data storage devices so as to present to a user a single data stack structure and to enable individual data storage devices to be freely removed and/or replaced and/or upgraded such that the data stack structure is automatically preserved independent of hardware over which it is distributed.