Elastic MapReduce (EMR) Hadoop service is integrated with the COS service. When you purchase an EMR cluster, if you select COS and make it available for your cluster, you can manipulate the data stored in COS with common Hadoop commands by running the following command.
cat data hadoop fs -cat /usr/hive/warehouse/hivewithhdfs.db/record/data.txt Modify directory or file permission hadoop fs -chmod -R 777 /usr Change file or directory owner hadoop fs -chown -R root:root /usr Create a folder hadoop fs -mkdir <paths> Send a local file to HDFS hadoop fs -put <localsrc> ... <dst> Copy a local file to HDFS hadoop fs -copyFromLocal <localsrc> URI View the storage usage of a file or directory hadoop fs -du URI [URI …] Delete a file hadoop fs -rm URI [URI …] Set the number of copies of a directory or file hadoop fs–setrep [-R] [-w] REP PATH [PATH …] Check for bad blocks of a cluster file hadoop fsck <path> [-move | -delete | -openforwrite] [-files [-blocks [-locations | -racks]]]
For more HDFS commands, please see the community documentation. If your cluster is a high-availability cluster (dual-namenode), you can see which namenode is active by running following command:
nn1 is the ID of namenode, which is generally nn1 and nn2 hdfs haadmin -getServiceState nn1 View current cluster report hdfs dfsadmin -report namenode exited safe mode hdfs dfsadmin -safemode leave