Step 7: Prepare the cluster for each user

Before users access the cluster, there are a few tasks you must complete to prepare the hosts for each user.

Make sure all hosts in the cluster have a Linux user account with the same name as the first component of that user's principal name. For example, the Linux account joe should exist on every box if the user's principal name is joe@YOUR-REALM.COM. You can use LDAP for this step if it is available in your organization.

note
Each account must have a user ID that is greater than or equal to 1000. In the /etc/hadoop/conf/taskcontroller.cfg file, the default setting for the banned.users property is mapred, hdfs, and bin to prevent jobs from being submitted using those user accounts. The default setting for the min.user.id property is 1000 to prevent jobs from being submitted with a user ID less than 1000, which are conventionally Unix super users.
Create a subdirectory under /user on HDFS for each user account (for example, /user/joe). Change the owner and group of that directory to be the user.
```
hadoop fs -mkdir /user/joe
hadoop fs -chown joe /user/joe
```
note
sudo -u hdfs is not included in the commands above. This is because it is not required if Kerberos is enabled on your cluster. You will, however, need to have Kerberos credentials for the HDFS super user to successfully run these commands. For information on gaining access to the HDFS super user account, see Step 5: Create the HDFS superuser.