If it turns out it's the upses that caught fire, one can't help but wonder if it would be a better idea to house the upses/backup power solutions in an adjacent smaller building outfitted with sprinklers perhaps?
Also, in the first part of a lithium battery fire, dropping water on them is quite explosive. It will eventually quench the fire but on the short run it will make it worse, filling the room with explosive hydrogen and poisonous lithium hydroxide. So when your water sprinklers engage over your UPS, you better be sure there's nobody around: https://www.youtube.com/watch?v=cTJh_bzI0QQ
AIUI being in a room during a halon dump is unpleasant but not too dangerous, but you really don’t want to be in there when the argonite release happens!
It's fun when someone accidentally dumps the halon system because they pressed the wrong button, and now halon has to be sourced for replacement.
Most high-end UPSes have a relay where you can run an active-high or active-low emergency power off (EPO) signal. The EPO can either be a button that is pressed manually by the staff, automatically via fire suppression system, or both/either.
Schneider-APC white paper (PDF)
* https://download.schneider-electric.com/files?p_File_Name=AS...
The EPO can also cut-off the HVAC so oxygen is no longer fed into the area, and smoke isn't (re-)circulated.
In the US, this is probably covered in NFPA 75, "Standard for the Fire Protection of Information Technology Equipment":
* https://www.nfpa.org/codes-and-standards/all-codes-and-stand...
So can have the more common water fire suppression in the day-to-day areas where people are more likely to be in, and have have non-water solutions. Water mist instead of 'traditional' sprinklers is also a thing in many places:
* https://res.mdpi.com/d_attachment/energies/energies-13-05117...