BUG-17431: (HDFS-5526) If you upgrade from HDP 2.0.9.1 to HDP 2.1, the DataNode cannot be rolled back to HDP 2.0.9.1. Contact Support for an update to fix this HDP 2.0.9.1 issue.
BUG-17431: (HDFS-5526) If you upgrade from HDP 2.0.9.1 to HDP 2.1, the DataNode cannot be rolled back to HDP 2.0.9.1. Contact Support for an update to fix this HDP 2.0.9.1 issue.