Cache coherency of a global address space of a cache can be maintained with one or more tier control units (TCUs). The global address space of the cache may be shared by multiple domains. Domains may include multiple controllers and a local interconnect operatively coupling the controllers to the cache. The local interconnect of each domain may maintain a cache coherency of a local address space of the cache shared by the controllers of the domain. The one or more TCUs may be operatively coupled to the local interconnects of the domains to maintain the cache coherency of the global address space.