Regarding 2:
This may seem somewhat contrived, but I tried to come up with some tech analogy.
Let's say that you have some analyzer which takes in a finite amount of physical matter, and then produces some dataset. The analysis is a destructive process, so that the analyzer will only be able to produce N different datasets - until it runs out of the physical matter it is analyzing.
The datasets are huge, and will take up all available memory. Before the next dataset is finished, you need to decide whether to store or delete/discard the current. The permanent storage can only hold one of these datasets, and it is impossible to write over it. Once you have stored a dataset permanently, the next ones will get discarded as soon as they've been generated.
Or something like that.
Edit: Wouldn't surprise me if there's some embedded system / machine out there that's bound to select stuff like that.