My curiousity about your personal situation is piqued by this statement. Did you work on the hardware or the software of such systems? There are very, very few systems in the world that clock in the millions per minute. Various financial services and exchanges (equities, bonds, commodities, forex, etc.), credit card processing and extremely large retail operations like WalMart are the class of operations that use computer environments that handle $525.6 billion or more per year of transactions so frequent that you can measure downtime on a $1M (or more) per minute basis.
If you were one of the people who architect and manage such environments, then you should be able to parlay that experience into your own business.
I was speaking in general terms. When you have a system go down in any manufacturing environment, depending on what the system is, you can shut down an entire facility in nothing flat. Anyone that has worked in such an environment knows that shuttting a line down for a few minutes mounts up costwise very rapidly. I worked in meatpacking years ago - where losing a 40 foot conveyer for 30 minutes cost the plant millions. You live or die by deadlines, contracts, overhead, etc. So, being down is a major expense. And when your Just in time system fails and you can't label goods, reconcile inventory, load a truck, etc for an hour... delphi loses mega bucks.