[sgeisler]

I read that all mainframe components, even CPUs, were redundant and hot-swappable and that instructions are executed on two separate CPUs to detect faults and correct them on the fly. That would make a lot of sense if your application requires high availability and assurance but isn't designed for it. I haven't heard of any standard server hardware that can give you HA or such assurance with a single machine, probably because you would not build any application dependent on that these days. It's probably cheaper to do in software.

[ideonode]

I remember hearing a story (probably apocryphal) about a mainframe that was so redundant that it had to be physically dismantled and moved from one datacentre to another across town, and did so whilst remaining up the entire time.

[travem]

Case in point, vSphere Fault Tolerance is a software approach that runs your workload in a VM where the CPU instructions are mirrored to another VM on another physical server to deliver redundancy against physical server loss.