Using the extend and overflow storage group types with fast replication

The SMS "extend" and "overflow" storage group types allow you to allocate data sets on volumes, or to extend data sets onto volumes that are not a part of a main source storage group. In most environments, SMS extend or overflow storage groups should not be used in a copy pool environment. These storage group types should only be used if all source storage groups utilizing a particular extend or overflow storage group and the extend or overflow storage group itself are all contained within the same copy pools. Extend and overflow storage groups must not be used if the source storage groups that are utilizing them are contained within different copy pools.