I attended at a client computer centre shortly after the bottles had cracked.
18 bottles in total, each the size of an acetylene bottle, linked in pairs but due to the system being accidently left in test mode, only the first two pairs cracked.
The suspended ceiling came down, and dumped piles of black dust over everything.
Three operators were in the room, one managed to drag another to the door where others were able to pull them out. The Operations Manager grabbed a breathing unit and went in to find the 3rd guy unconscious and managed to drag him out. He took quite a while to get resuscitated but survived.
Halon sinks to the floor, so if you are prone, you get to buy the farm quickly.
The building had to be evacuated until the room could be purged by the fire service.
Deadly stuff which I believe was banned in computer rooms shortly after. I doubt anything in a cargo hold could survive, and the potential (in my mind) for distribution of the gas through the aircon still fills me with dread.