Fig. 2

IBF vs. the HIBF. Given an input of eight user bins (UBs), subfigure a displays the layout of a normal IBF storing the content of the UBs, represented by the inner, lightly colored cylinders, in one technical bin (TB) each. The outer cylinders represent the size of the TBs and visualizes the wasted space. The horizontal rectangular bar represents the layout, indicating which UBs, identified by their ID (A-H), are stored in which TB. The same semantics hold for subfigure b which displays the corresponding HIBF with a maximum of 5 TBs on each level. In this example, UB A is split into the first two TBs in IBF-1, while UBs D-H are merged into the last TB. The merged bin requires a second lower-level IBF (IBF-2) storing the content of UB D-H in individual TBs. The size is given in exemplary numbers