MAC address pools are now bound to the cluster instead of the data center because certain environments require MAC address pools on the cluster level.
On the REST layer, the mac_pool attribute was added to the cluster, and can be set or queried. The StoragePool resource (represents the Data Center) was also altered. When updating its mac_pool_id, all clusters in given Data Center will be updated to use this MAC address pool. When StoragePool is queried using the REST GET method, the ID of the MAC address pool will be reported only when all clusters in the given Data Center are using the same MAC address pool. Otherwise user needs to use the Cluster resource to get the MAC address pool of each individual cluster.