I used to manage some high-end phone switches. These switches being built in Israel.

I watched them pull out all (four redundant) processor boards, cut with diagonal pliers one whole side of the backplane... not a single phone was lost and not a single phonecall was missed.

These switches had "card processors" and 4 way redundant backplanes. So if the processors died and much of the backplane failed... it would continue to function at 100%.

They built this to take shotgun blasts from point blank range. Also to take a fragmentary grenade out side the cabinet and continue to work. They also have kits to deal with incendiary grenades and fires.

... gah, been trying to think of the company name... grrr.