That, plus you typically dont go and hangout on the DC floor, only the personel who is really required gets to go in.
Holding doors was always a problem, but I guess that nowadays badges can have RFID or some other kind of wireless tracking so even if you hold the door, people in the control room can always know how many people are in each room, all the time. It's like 6 years now since the last time I was in a datacenter...
times changed. I remember my friend bunch of years ago complaining to me that the DC at their branch of a large well known transnational was the favorite place of the employees for various informal activities, including that he was constantly dealing with used drug paraphernalia being left all over the place.
Answer to the comment below: yep, mostly syringes/needles.
Door locks during an emergency are usually denoted to be fail-open so someone doesn't get trapped, though that may differ depending on the security level of the facility.
sounds like on a submarine. On submarine the people who couldn't make it out of the sealed section in time, would use the personal breathing device - i wonder if AWS has such thing in the datacenter, and how do they make sure that all people are out from a huge datacenter. Several years ago a Russian nuclear sub on a sea trials after refit had the fire suppression system activated in the section where a bunch of people gathered - crew and the navy yard civilians, probably they celebrated drinking and smoking - and insufficient number of the breathing devices combined with lack of skills to quickly use it on the part of the civilians resulted in 20 deaths and 40 injured (lung damage, etc.), mostly the civilians.