Wonder how it works in real life. Protecting against component failures is nice but there's no real mention of software reliability. If for example you are running vSphere on it, and you need to install patches that is still downtime(could mitigate that more with a pair of systems but seems quite overkill). Or worse if the OS crashes(host or guest).
Closest comparison I can think of off top of my head https://en.wikipedia.org/wiki/NonStop_(server_computers)
But that system seems to have software tolerance as well
"NonStop OS is a message-based operating system designed for fault tolerance. It works with process pairs and ensures that backup processes on redundant CPUs take over in case of a process or CPU failure. Data integrity is maintained during those takeovers; no transactions or data are lost or corrupted. "
But of course you probably can't run things like vSphere on NonStop.
vSphere itself has had fault tolerance for a long time which would cover a lot of use cases where you have to be protected against component failure but there are of course limitations (less now than originally it was limited to 1 vCPU, looks like current limit is 8 vCPU) - https://www.vmware.com/products/vsphere/fault-tolerance.html