running sphinx on multiple machines or a single instance

I have an app , using ruby and thinking sphinx . right now each one of my web servers running a local sphinx daemon. I don't know if it's better to run a s开发者_StackOverflowingle instance of sphinx and have all the machines to point to this one or keep the current scenario ? the problem with the current one if the fact each machine does index build and rebuild which is a way is redundant and cause an extra load on the data base.(i'm running index and delta every 30 minutes) , on the other hand I don't what will be the down site of sphinx over the network . What's the best approach ?