One Terracotta instance needs to act as Terracotta server in the cluster. This can be a Terracotta instance on the same machine as one of the Servoy Application Servers in the Servoy Cluster or it can be a dedicated Terracotta instance on a dedicated machine.
When using a Terracotta instance on a machine that also runs one of the Servoy Application Servers, make sure that the machine either gets less load on the Servoy Application Server by using a Load Balancer, or make sure that the machine is capable of handling a higher load.