Address/memory management for a gigantic LISP environment or, GC considered harmful

The possibility of incredibly cheap, fantastically large media for storage gives rise to a realistic LISP memory management scheme under which GC may be postponed for days, or even indefinitely; the idea is encapsulated in the acronym "DDI" --- "GC? Don't Do It!". Tertiary memory is used to archive pages of the LISP environment which are perhaps reclaimable. but which have not been proven so; whereas the standard technique of "paging" is used to swap active data from the main memory to a secondary store such as magnetic disk. Some scenarios are presented considering a variety of currently-available technologies, and of one speculative possibility --- videodisc --- by which a requisite compactifying GC would be done "overnight", or over the weekend. With enough tertiary available, one design could last for over 12 years without a GC. "Write-once" memories, probably unusable for most applications, would not be at a disadvantage here.