[j-nsp] MX10k and PTX10k fabric swap experiences

[Saku Ytti]

The official docs give 3min time to swap fabric, due to cooling
restrictions. (why are the power supplies vertically, not
horizontally? Why is there two wide fans, instead of 3 narrower? So
you'd expose 2 fabric cards removing 1 fan. Exposing less and having
2/3 of cooling in place? I am industrial design ignorant, but seems
odd).

I'd like to hear operational experience people have, anything is
welcome, no matter now anecdotal, but ideally.
  a) how many watts were you pulling
  b) what temperature is the cold isle
  c) how long have you operated the chassis with single fan without failure


Thanks!
-- 
  ++ytti