2.7. Modify HDFS Configurations

You may need to modify your hdfs-site configuration and/or your core-site configuration.

To check if you need to modify your hdfs-site configuration, on the Ambari Server host:
```
/var/lib/ambari-server/resources/scripts/configs.sh -u $AMBARI_USER -p $AMBARI_PW -port $AMBARI_PORT get localhost $CLUSTER_NAME hdfs-site
```
If you see any of the following properties, you must delete them from your hdfs-site configuration.
- dfs.nameservices
- dfs.client.failover.proxy.provider.${NAMESERVICE_ID}
- dfs.ha.namenodes.${NAMESERVICE_ID}
- dfs.ha.fencing.methods
- dfs.ha.automatic-failover.enabled
- dfs.namenode.http-address.${NAMESERVICE_ID}.nn1
- dfs.namenode.http-address.${NAMESERVICE_ID}.nn2
- dfs.namenode.rpc-address.${NAMESERVICE_ID}.nn1
- dfs.namenode.rpc-address.${NAMESERVICE_ID}.nn2
- dfs.namenode.shared.edits.dir
- dfs.journalnode.edits.dir
- dfs.journalnode.http-address
- dfs.journalnode.kerberos.internal.spnego.principal
- dfs.journalnode.kerberos.principal
- dfs.journalnode.keytab.file
  Where ${NAMESERVICE_ID} is the NameService ID you created when you ran the Enable NameNode HA wizard.
To delete these properties, execute the following for each property you found. On the Ambari Server host:
```
/var/lib/ambari-server/resources/scripts/configs.sh -u $AMBARI_USER -p $AMBARI_PW -port $AMBARI_PORT delete localhost $CLUSTER_NAME hdfs-site property_name
```
Where you replace property_name with the name of each of the properties to be deleted.
Verify that all of the properties have been deleted. On the Ambari Server host:
```
/var/lib/ambari-server/resources/scripts/configs.sh -u $AMBARI_USER -p $AMBARI_PW -port $AMBARI_PORT get localhost $CLUSTER_NAME hdfs-site
```
None of the properties listed above should be present.

To check if you need to modify your core-site configuration, on the Ambari Server host:

/var/lib/ambari-server/resources/scripts/configs.sh -u $AMBARI_USER -p $AMBARI_PW -port $AMBARI_PORT get localhost $CLUSTER_NAME core-site

If you see the property ha.zookeeper.quorum, it must be deleted. On the Ambari Server host:

/var/lib/ambari-server/resources/scripts/configs.sh -u $AMBARI_USER -p $AMBARI_PW -port $AMBARI_PORT delete localhost $CLUSTER_NAME core-site ha.zookeeper.quorum

If the property fs.defaultFS is set to the NameService ID, it must be reverted back to its non-HA value. For example:

“fs.defaultFS” : “hdfs://name-service-id”
The property fs.defaultFS needs to be modified as it points to a NameService ID

“fs.defaultFS” : “hdfs://nn01.mycompany.com” 
The property fs.defaultFS does not need to be changed as it points to a specific NameNode and not a NameService ID

To revert the property fs.defaultFS to the NameNode host value, on the Ambari Server host:

/var/lib/ambari-server/resources/scripts/configs.sh -u $AMBARI_USER -p $AMBARI_PW -port $AMBARI_PORT set localhost $CLUSTER_NAME core-site fs.defaultFS hdfs://${NAMENODE_HOSTNAME}

Verify that the core-site properties are now properly set. On the Ambari Server host:
```
/var/lib/ambari-server/resources/scripts/configs.sh -u $AMBARI_USER -p $AMBARI_PW -port $AMBARI_PORT get localhost $CLUSTER_NAME core-site
```
The property fs.defaultFS should be set to point to the NameNode host and the property ha.zookeeper.quorum should not be there.

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