Known Issues in HDFS
Learn about the known issues in HDFS, the impact or changes to the functionality, and the workaround.
- OPSAPS-60958: The dfs.access.time.precision and dfs.namenode.accesstime.precision parameters are available in Cloudera Manager > HDFS > Configuration.
- You must configure both the dfs.access.time.precision and dfs.namenode.accesstime.precision parameters with the same value as Cloudera Manager still sends both the parameters to HDFS service configuration.
- ENGESC-19334: After configuring multiple NameNodes, with heavy read and write workloads in the cluster, there are chances of performance impact in terms of slowness on the client side.
- This is because of the additional NN retry or probe introduced by the extra NN.
- OPSAPS-64307: In the case when on a cluster the JournalNodes were restarted recently, the "Add new NameNode" wizard for HDFS service might fail to bootstrap the new NameNode, if there wasn't a new fsImage created since the restart of the JournalNodes, but during restarting them the edit logs were rolled in the system.
- If the bootstrap fails during the "Add new NameNode" wizard, then do the following steps:
- Delete the newly added NameNode and FailoverController
- Move the active HDFS NameNode to safe mode
- Do a Save Namespace operation on the active HDFS NameNode
- Leave safe mode on the active HDFS NameNode
- Try to add the new NameNode again
- OPSAPS-64363: Deleting of additional Standby Namenode does not delete the ZKFC role and this has to be done manually.
- None
- OPSAPS-63558: Snapshot diff based HDFS replications do not provide correct file delete and rename counters through the API.
- The number of files deleted and renamed by DistCp for snapshot based replications can be checked in the logs provided by DistCp on the standard error output.
- CDPD-28459: After performing an upgrade rollback from CDP 7.1.7 to CDH6, you may see the following error when restarting the DataNodes: ERROR datanode.DataNode: Exception in secureMain java.io.IOException: The path component: '/var/run/hdfs-sockets' in '/var/run/hdfs-sockets/dn' has permissions 0755 uid 39998 and gid 1006. It is not protected because it is owned by a user who is not root and not the effective user: '0'.
- You must run the command described in the error message "chown root /var/run/hdfs-sockets". After this, the DataNode will restart successfully.
- CDPD-28390: Rolling restart of the HDFS JournalNodes may time out on Ubuntu20.
- If the restart operation times out, you can manually stop and restart the Name Node and Journal Node services one by one.
- OPSAPS-60832: When decommission of DN runs for a longer time and when decommission monitor's kerberos ticket expires, it is not auto-renewed. Decommission of DN is not completed in CM as decommission monitor fails to fetch the state of DN after kerberos ticket expiry.
- Decommission state of DN can be fetched using CLI command, i.e, hdfs dfsadmin -report.
- OPSAPS-55788: WebHDFS is always enabled. The Enable WebHDFS checkbox does not take effect.
- None.
- OPSAPS-63299: Disable HA command for a nameservice does not work if the nameservice has more than 2 NNs defined.
- None
- OPSAPS-63301: Deleting nameservice command does not delete all the NNs belonging to the nameservice, if there are more than two NNs that are assigned to the nameservice.
- None
- CDPD-50044: Data node tab loading issue in the name node UI
- When clicking on the data node tab, the message
NameNode is still loading. Redirecting to the Startup Progress page
appears. - Unsupported Features
-
The following HDFS features are currently not supported in Cloudera Data Platform:
- ACLs for the NFS gateway (HADOOP-11004)
- Aliyun Cloud Connector (HADOOP-12756)
- Allow HDFS block replicas to be provided by an external storage system (HDFS-9806)
- Consistent standby Serving reads (HDFS-12943)
- Cost-Based RPC FairCallQueue (HDFS-14403)
- HDFS Router Based Federation (HDFS-10467)
- NameNode Federation (HDFS-1052)
- NameNode Port-based Selective Encryption (HDFS-13541)
- Non-Volatile Storage Class Memory (SCM) in HDFS Cache Directives (HDFS-13762)
- OpenStack Swift (HADOOP-8545)
- SFTP FileSystem (HADOOP-5732)
- Storage policy satisfier (HDFS-10285)