I have a small 6U rack in my hallway which is where all the server stuff sits. There are 1U UPS units, but I haven’t had the need for it yet. However after replacing motherboard on this current machine I forgot to turn on option for auto start after power failure. My servers are mostly for collecting data regarding temperature, humidity and other metrics around the house, glass house and other parts. Same machine also collects surveillance data from cameras around the property which detect human and animal shapes.
So since machine rarely does long term calculations or data processing it’s okay that it doesn’t have UPS, since no data would be coming anyway without power.