Yes you can. Although we use the term 'cluster' on our website and in our documentation, usage of this feature is not restricted to common clustering scenarios like fail-over and load-balancing. By enabling different sites on different servers, you have the capability of centrally managing a set of CompleteFTP instances in which each instance serves a different role. Since you can enable different users on different sites, you can implicitly restrict access of particular users to particular instances and, since each user can only access a specified set of folders, you can also implicit limit access to the Windows file-system on a per-instance basis.