Step 16: Prepare the Cluster for Each User

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

Make sure all hosts in the cluster have a Unix user account with the same name as the first component of that user's principal name. For example, the Unix 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 from 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
```

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