The ALICE data acquisition system needs to balance its capacity to record the steady stream of very large events resulting from central collisions, with an ability to select and record rare cross-section processes. These requirements result in an aggregate event building bandwidth of up to 2.5 GByte/s and a storage capability of up to 1.25 GByte/s, giving a total of more than 1 PByte of data every year. As shown in the figure, ALICE needs a data storage capacity that by far exceeds that of the current generation of experiments. This data rate is equivalent to six times the contents of the Encyclopædia Britannica every second.