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Restore HDFS permissions

  • Artikkeli

Important

The Microsoft SQL Server 2019 Big Data Clusters add-on will be retired. Support for SQL Server 2019 Big Data Clusters will end on February 28, 2025. All existing users of SQL Server 2019 with Software Assurance will be fully supported on the platform and the software will continue to be maintained through SQL Server cumulative updates until that time. For more information, see the announcement blog post and Big data options on the Microsoft SQL Server platform.

HDFS access control lists (ACLs) modifications may have affected the /system and /tmp folders in HDFS. The most likely cause of ACL modification is a user manually manipulating the folder ACLs. Directly modifying permissions in /system folder and /tmp/logs folder are not supported.

Symptom

A spark job is submitted through ADS and it fails with SparkContext initialization error and AccessControlException.

583 ERROR spark.SparkContext: Error initializing SparkContext.
org.apache.hadoop.security.AccessControlException: Permission denied: user=<UserAccount>, access=WRITE, inode="/system/spark-events":sph:BDCAdmin:drwxr-xr-x

Yarn UI shows application ID in KILLED status.

When you try to write to the folder as the domain user, it also fails. You can test with the following example:

kinit <UserAccount>
hdfs dfs -touch /system/spark-events/test
hdfs dfs -rm /system/spark-events/test

Cause

The HDFS ACLs were modified for BDC user domain security group. Possible modifications included ACLs for /system and /tmp folders. Modifications of these folders are not supported.

Verify the effect in the Livy logs:

INFO utils.LineBufferedStream: YYYY-MM-DD-HH:MM:SS,858 INFO yarn.Client: Application report for application_1580771254352_0041 (state: ACCEPTED)
...
WARN rsc.RSCClient: Client RPC channel closed unexpectedly.
INFO interactive.InteractiveSession: Failed to ping RSC driver for session <ID>. Killing application

The YARN UI shows applications in KILLED status for the application ID.

To get the root cause of RPC connection close, check the YARN application log for app corresponding to the application. In the preceding example, it refers to application_1580771254352_0041. Use kubectl to connect to the sparkhead-0 pod, and run this command:

The following command queries the YARN log for the application.

yarn logs -applicationId application_1580771254352_0041

In the results below the permission is denied for the user.

YYYY-MM-DD-HH:MM:SS,583 ERROR spark.SparkContext: Error initializing SparkContext.
org.apache.hadoop.security.AccessControlException: Permission denied: user=user1, access=WRITE, inode="/system/spark-events":sph:BDCAdmin:drwxr-xr-x

The cause may be that the BDC User was recursively added to the HDFS root folder. This may have affected the default permissions.

Resolution

Restore the permissions with the following script: Use kinit with admin:

hdfs dfs -chmod 733 /system/spark-events
hdfs dfs -setfacl --set default:user:sph:rwx,default:other::--- /system/spark-events
hdfs dfs -setfacl --set default:user:app-setup:r-x,default:other::--- /system/appdeploy
hadoop fs -chmod 733 /tmp/logs
hdfs dfs -setfacl --set default:user:yarn:rwx,default:other::--- /tmp/logs