If that includes OS components Like windows, that is a real challenge.
Exactly what does server will not fail mean ? There are alot of complex components and programmes in ROM. Where I work I doubt a server would last more that about 1-2 years without something going wrong and we use Compaq, Sun and Dell.
This is a 'triple redundant' system, which basically means all three have to fail at the same time and only 'Hardware or OS' is the covered (network down etc. not covered). One unit may fail, then be repaired and put back on line, this is expected. The price tag is about $25,000 to $30,000 per year, so I guess they've done the math.