Error Message "Permission denied" Is Displayed When HDFS and Yarn Are Started

Issue

An error is reported during HDFS and Yarn startup.

Symptom

HDFS and Yarn fail to be started. The following error information is displayed: /dev/null Permission denied

Cause Analysis

The /dev/null permission value of the VM is changed to 775.

Procedure

1. Log in to any master node in the cluster as user root.
2. After successful login, run the chmod 666 /dev/null command to change the permission value of /dev/null to 666.
3. Run the ls -al /dev/null command to check whether the new permission value of /dev/null is 666. If it is not, change the value to 666.
4. After the modification is successful, restart HDFS and Yarn.