Very cool work! I wonder the same, for a 'cluster' I'm expecting performance and large memory for example for scientific computing. Other than that I couldn't think of any other use cases. If anyone could enlighten me? Cheers
I made a cluster of 9 pi's for a work project, not for the computing power but for the segmentation. I had 8 pieces of equipment that needed to be monitored while undergoing various physical tests. A simple app was developed that would run on each piece being tested and communicate over the ethernet port each millisecond back to a pi, which then forwarded the on/off status to a central pc connected to the 9th pi acting as a wifi access point. This computer served as the monitor/display and logger of the system so we could see at a glance if everything was green and reporting or not.
It was important that each piece be physically isolated so that we knew the whole path was operational and nothing was short circuiting via something else's network connection. You could have accomplished something similar with VLANs and some routes, but this allowed for easier troubleshooting and to explain to the powers that be how things were guaranteed isolated because they could see it. Plus it looked cool.
yes, if you want to optimize a worst-case MPI-cluster, then a Pi (4) might be optimal for you (because sadly, 4 measly ARM cores with 100MBit/s is a some magnitudes removed from 100 cores and 100GBit/s Infiniband). But then you can also use a stack of old desktops, which is cheaper and you can just throw in a standard image and everything (including CUDA and MKL) can work.
