Cache optimization. Cache access rates for tenants sharing the same cache are monitored to determine an expected cache usage. Factors related to cache efficiency or performance dictate occupancy constraints. A request to increase cache space allocated to a first tenant is received. If there is a second cache tenant for which reducing its cache size by the requested amount will not violate the occupancy constraints for the second cache tenant, its cache is decreased by the requested amount and allocated to satisfy the request. Otherwise, the first cache size is increased by allocating the amount of data storage space to the first cache tenant without deallocating the same amount of data storage space allocated to another cache tenant from among the plurality of cache tenants.