16:03 Oct 20, 2010 

I'd have said it was more like 'redondance à commutation automatique'; as for the 1:2, I'm not familiar with this expression, but my guess would be that it refers to the fact that each device has not one but two back-up devices assigned to it. We talk about "100% redundancy" when every device is backed up by another one; so I can only suppose this is referring to "200% redundancy" — real 'belt-and-braces' stuff, this, but it looks like it's pretty mission-critical!