我正在学习本教程（目前为2.7.2）https://hadoop.apache.org/docs/stable/hadoop-project-dist/hadoop-common/singlecluster.html 在ubuntu14.04.4上的hadoop的早期版本（2.0.0alpha）。
但是，运行 sbin/start-dfs.sh 格式化namenode后，会出现以下错误：

17/01/06 11:46:20 WARN util.KerberosName: Kerberos krb5 configuration not found, setting default realm to empty
Starting namenodes on [localhost]
localhost: mkdir: cannot create directory ‘/username’: Permission denied
localhost: chown: cannot access ‘/username/username’: No such file or directory
localhost: starting namenode, logging to /username/username/hadoop-username-namenode-hostname.out
localhost: /home/username/project/hadoop/hadoop-dist/target/hadoop-2.0.0-alpha/sbin/hadoop-daemon.sh: line 149: /username/username/hadoop-username-namenode-hostname.out: No such file or directory
localhost: head: cannot open ‘/username/username/hadoop-username-namenode-hostname.out’ for reading: No such file or directory
localhost: mkdir: cannot create directory ‘/username’: Permission denied
localhost: chown: cannot access ‘/username/username’: No such file or directory
localhost: starting datanode, logging to /username/username/hadoop-username-datanode-hostname.out
localhost: /home/username/project/hadoop/hadoop-dist/target/hadoop-2.0.0-alpha/sbin/hadoop-daemon.sh: line 149: /username/username/hadoop-username-datanode-hostname.out: No such file or directory
localhost: head: cannot open ‘/username/username/hadoop-username-datanode-hostname.out’ for reading: No such file or directory
Starting secondary namenodes [0.0.0.0]
0.0.0.0: mkdir: cannot create directory ‘/username’: Permission denied
0.0.0.0: chown: cannot access ‘/username/username’: No such file or directory
0.0.0.0: starting secondarynamenode, logging to /username/username/hadoop-username-secondarynamenode-hostname.out
0.0.0.0: /home/username/project/hadoop/hadoop-dist/target/hadoop-2.0.0-alpha/sbin/hadoop-daemon.sh: line 149: /username/username/hadoop-username-secondarynamenode-hostname.out: No such file or directory
0.0.0.0: head: cannot open ‘/username/username/hadoop-username-secondarynamenode-hostname.out’ for reading: No such file or directory

我看到过很多关于更改所有者的帖子，但是我没有为hadoop创建一个特殊的用户，所以sshing into localhost仍然将用户显示为我的“用户名”。很明显，hadoop文件夹是我的，我运行chown也是为了确保，所以为什么这里还有权限问题呢？