A company called Descartes Labs has become number 136 on the top500 supercomputer list just by paying for a large enough collection of nodes on its Amazon Web Services account <https://www.theregister.co.uk/2019/06/20/supercomputer_aws/>. However, Dr Paul Calleja, directory of the University of Cambridge Research Computing Services, argues that this is not really cost-effective compared to buying your own actual gear, and the I/O performance is not that good anyway. Such a cloud cluster may score well on LINPACK, but not so well on real-world supercomputing problems. Dr Calleja advocates using OpenStack to build a “hybrid” combination of on-premise physical hardware backed up by cloud services for those times when you need a bit of a (temporary) boost. And for learner supercomputer drivers, there is always the option of a Raspberry π cluster to practise on, before being allowed behind the wheel of a real big-iron machine ...