I’d say 15+ years ago, they were very powerful relative to other solutions on the market during those times. But I agree that’s no longer the case when compared

I’d say 15+ years ago, they were very powerful relative to other solutions on the market during those times. But I agree that’s no longer the case when compared to modern server racks. I pointed out that Redbook about HA features since it’s a major differentiator of mainframes even today, but there are also these that document other features: https://www.redbooks.ibm.com/redbooks/pdfs/sg248950.pdf#page415 https://www.redbooks.ibm.com/redbooks/pdfs/sg248950.pdf#page... https://www.redbooks.ibm.com/redbooks/pdfs/sg246366.pdf#page415 https://www.redbooks.ibm.com/redbooks/pdfs/sg246366.pdf#page... You can find 1 or more books that go into a deep dive of every chapter. IBM has taken input from the biggest companies in the world over many decades to run as many of their workloads as possible. They’ve honed everything in their software and hardware to do so, down to developing specific cpu instructions to support specific use cases. If all of this doesn’t convey an extremely feature rich system, I’d like to hear why you think otherwise.