Keeping tradition with doing things backwards, I’ve finally got a UPS for the rack (mounted in the bottom of the stack). Got a PowerWalker VI 2200R. Its a 2U unit which is all the space I’ve got left in the rack. Decent price and decent I/O with USB, serial and a slot-in for network expansion + 4 IEC outputs. Its powering everything in the rack and connected via USB to my main server which runs a NUT server that other machines can connect to. A calibration run (100-80%) puts the runtime at about 20 min. Long enough that I’m comfortable setting things to shut down when 20% capacity remains. Summary, I sleep better now.
Had to replace my UPS battery just a few days ago after a power outage reminded me that a replacement was well overdue. I share your feeling, now I can sleep knowing a power blip won’t knock out my servers and mess up my data.