Packet filtering is used in the first generation of firewalls and does not keep track of the state of a connection. Stateful packet filtering does. Source: WALLHOFF, John, CISSP Summary 2002, April 2002, CBK#2 Telecommunications and Network Security (page 6), /Documents/CISSP_Summary_2002/index.html.

This is the function of a tape robot/changer working on a media library / jukebox. We can get as many as 32 / 64 or even more tapes action as a single logical unit. You can have a robot that changes and retrieves the different tapes when they are needed, so you see the whole bunch of tapes as it's a single logical storage solution for you. This kind of solutions are very expensive.