What are the disadvantages of in row cooling in a data center?

One of the biggest disadvantage of in-row cooling is the routing of chilled water/refrigerant piping within the DATA hall. However, there are smart system such as leak detection to identify threats due to leakages in nuisance.

I think they suit the best for data center env provided that you have filled racks n large qty of servers. Still i prefer having a n+1 config

I can only think of2 situations where you should not use in-row cooling.... if the rack capacity is too low, in that case the high initial cost of multiple in-row cooling will not be justified or if the white space is too limited and cannot spare the extra space needed for the cooling units