The most bad-ass server I've ever had the pleasure of working with was a Digital VAX 11/750 generations ago. It was *built* to be reliable from the very first rivet.
Oh sure, my pocket phone has far more power, memory, and storage. Despite the ample square footage of my "McMansion" house, It would not have fit in my kitchen. It ate power like global warming really was a myth. But as a server, it was in its own class.
It would automatically detect memory that was failing and rebuild from memory (like ECC) but then would remap that address so it would no longer be used.
You could upgrade its CPUs one at a time without shutting it down.
It was like a hoover with data, versioning files was intrinsic to how the O/S worked.
One time, the A/C in the computer room went out. It mapped *everything* in RAM to disk as the temperature rose and the chips became unreliable. We literally pulled the plug on it because it was completely unresponsive, as all operations were working directly off HDD. When the A/C was fixed and it was powered up late that night, it spooled all of RAM out of the HDD swap, and everybody's workstation resumed exactly where they had left off that afternoon - we couldn't find any data loss at all.
I will forever bow in deference to the greatest server I have ever had the pleasure of working on. How HP managed to acquire such a legacy and turn its back... part of me cries inside.