I present to you "Commercial Fault Tolerance: A Tale of Two Systems" [2004][0] - a paper comparing the similarities and differences towards reliability/available/integrity between Tandem Nonstop and IBM Mainframe systems,

and the book "Reliable Computer Systems - Design and Evaluation"[1] which has general info on reliability, and specific looks at IBM Mainframe, Tandem, and Stratus, plus AT&T switches and spaceflight computers.

[0] https://pages.cs.wisc.edu/~remzi/Classes/838/Fall2001/Papers...

[1] https://archive.org/download/reliablecomputer00siew/reliable...