Eligibility for DFSMShsm space management of non-SMS-managed storage is determined on a volume basis. Non-SMS-managed volumes that are to be automatically managed by DFSMShsm are known as primary volumes. That is, all the data sets on a volume are managed to the same specification, whether for days-not-used on the primary volume, age for deletion, or permission for automatic migration. In addition, DFSMShsm chooses the volume to receive the recalled data sets based on the volume pools you have defined, as well as the characteristics given the volumes when you defined them.