Register org.apache.hadoop.hbase.backup.BackupHFileCleaner through hbase.master.hfilecleaner.plugins.

org.apache.hadoop.hbase.backup.BackupHFileCleaner is responsible for keeping bulk loaded hfiles so that incremental backup can pick them up.

Register org.apache.hadoop.hbase.backup.BackupObserver through hbase.coprocessor.region.classes.

org.apache.hadoop.hbase.backup.BackupObserver is notified when bulk load completes and writes records into hbase:backup table.