6.1. Known Issues for Hadoop

JobTracker UI, JMX queries, and RPC calls somtimes hang in HA mode.
Problem: JobTracker becomes slow and non-responsive in HA mode because dfs.client.retry.policy.enabled is not set to 'final' and 'false' for the JobTracker.
Workaround:Set dfs.client.retry.policy.enabled to 'final' and 'false' only for the JobTracker. Clients (such as MapReduce, Pig, Hive, Oozie) should still be set to 'true' in HA mode.
Problem: While uploading files to NFS-MountDir, the following error is reported in the DataNode log file:
```
INFO org.apache.hadoop.hdfs.nfs.nfs3.OpenFileCtx: requesed offset=4980736 and current filesize=0
```
Workaround: On some environments, especially for virtualized environments, copying large files of size close to 1GB fails intermittently. This issue is expected to be addressed in the upcoming release.
Use of init.d scripts for starting or stopping Hadoop services, is not recommended.