In this case, more expensive high capacity hardware is used for the fast traffic while the bulk traffic is handled by commodity hardware with large disk partitions.

The unit of procurement for large installations, however, will almost certainly be the "pod." In that context, adding capacity one server or disk at a time starts to make little sense.

Per-disk capacity now exceeds a terabyte, but a disk can nonetheless fill up quickly with large data files, lengthy log files, images, and media files such as movies.