Water..... We started out with one rain catchment tank up by the house, and a second down by the main gardens. Over time we added a back up tank for the house, and a series of small water storage units for the gardens and livestock. These small units consist of ponds, troughs, water totes, multiple heavy duty trashcans. Plus we keep around a dozen glass jugs with emergency drinking water in the house.
Electricity.... Initially we had one solar electric system. Over time we added a generator, then later, a portable one for doing jobs around the farm. Then expanded to a second small solar system to run the frig and freezer.
Small power tools.... The ones I use a lot, I have back ups for. So on this farm you'll find two lawnmowers, two chainsaws, two tillers, two light duty weedwackers, even two ATVs. These are items used almost every day, and if one breaks it would be a real bummer. So as time allowed and I could justify the expense, I added back ups. One of the pair resides up by the house while the other is in the barn....except for the ATVs. Both reside at the house and I just alternate each day which one I use, thus keeping them both in running shape. I tend to have the same habit for hand tools, keeping one in the barn and it's mate in the truck or tool area by the house. I have to let you in on a little secret. Hubby keeps his favorite tools in a case on his side of the bedroom closet. He claims possession of the back up tools so that I don't migrate them down to the barn or inside my truck. Smart man!
Breeding rams.... Two adult breeding sires, Ramrod and Ramsalot. And a ram lamb waiting in the wings -- Rambutan.
Vehicles..... Two. A decent truck and a used passenger car. We've been known to have 3 at times.
Food sources.....lots of redundancy here. Stores are available of course, but we also grow food, have developed a trading system, and can forage.
Firewood .... I don't think we will run out of firewood on our property, but we have established ties where we can harvest wood from others properties via a work trade system.
I know that there is much talk nowadays about cutting back, minimalizing one's material goods, decluttering, but I am more comfortable having back up items. In the case of work clothes, I have dozens of socks, shorts, and tops. One never knows when a long stretch of rain will happen and laundry won't dry, it's so nice knowing that I'm not going to run out of farm clothes. And the extra blankets I stored on the closet shelf really were a blessing this winter when the days got chilly and damp. By the way, I'm a cheap bugger and buy those things at our dump thrift store for very, very little.
Needless to say, I'm comfortable with redundancy. I've never been one for all-in-one set ups. For instance, when the latest & greatest computer printer came out that was also a copier, fax machine, and who knows what else, hubby wanted to go out and buy it to replace all our multiple office machines. My response was, if it dies then we can't fax, print, copy, etc. We're up the creek without a paddle. Yes, he bought it, but I never ditched my old fax machine, copier, or printer. They just moved over to my side of the office. Hubby and I had different ways of thinking.