As opposed to a raised floor cabling deployment an overhead deploymet has all the cabling such as power network and so on running above a false overhanging ceiling and are terminated through the ceiling and rack vents to the Rack patch panels.
One of the key benefit of false ceiling based cabling is that it is less expensive that a raised flooring. Even sometimes if the cooling system is not going to share the same false ceiling then a false ceiling can be completely avoided and only simple raceways can be mounted on the true ceiling and cables can pass through that. It would obviously cut down your cost significantly but the aesthetic look of the room will go for a toss. Plus, as the wires are open in this case, they are more prone to accidental damage.
Also, here gravity plays a major role in disturbing the deployment. Due to the weight of the wire itself, they can come out from the patch panel and get disconnected. So, here try avoiding any kind of suspended cabling and try to use the cables which get properly locked after connecting.
But one more major issue with overhead wiring is that in such case if you are going to couple the same space ( between the false and true ceiling ) for both cabling and circulating chilled air, it become somewhat difficult, because by virtue, hot air is supposed to rise up and cold air is supposed to settle down, and hence pushing cold air from top instead of using the top for venting out the hot air from the top is not the ideal situation.
And if you even don’t couple both cabling and cooling to the suspended ceiling then also it posses a challenge because you can’t have exhaust vents on the top because first the cable will get bad due to the constant flow of hot air through it and second they will create obstacles for the hot air to go out efficiently making it difficult. But for a small datacenter with lesser number of servers and racks, keeping the cost factor in mind suspended ceiling is a better choice