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https://issues.apache.org/jira/browse/HDFS-5939?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13907615#comment-13907615
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Haohui Mai commented on HDFS-5939:
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bq. The case reported in this bug is about no datanode is running, which is
about unhealthy cluster and definitely need to catch operator's attention. So I
think it makes sense to log a message in server log. Do you still think we
don't need to log an error there? It could save the operator time to
investigate the problem.
Personally I think it is an overkill. Note that if this happens, it means that
either (1) all datanodes are dead, or (2) there at least one block is missing
(i.e., no datanodes can serve it) in HDFS. Both the web UI and the monitoring
applications (e.g., Ambari / CDH) would catch it much earlier before the
operator looks into the log. The log has little value since it cannot flag the
error at the first place, and it provides sufficient information to reproduce
the error (in this case only the client can reproduce it in a reliable way).
> WebHdfs returns misleading error code and logs nothing if trying to create a
> file with no DNs in cluster
> --------------------------------------------------------------------------------------------------------
>
> Key: HDFS-5939
> URL: https://issues.apache.org/jira/browse/HDFS-5939
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs-client
> Affects Versions: 2.3.0
> Reporter: Yongjun Zhang
> Assignee: Yongjun Zhang
> Attachments: HDFS-5939.001.patch, HDFS-5939.002.patch
>
>
> When trying to access hdfs via webhdfs, and when datanode is dead, user will
> see an exception below without any clue that it's caused by dead datanode:
> $ curl -i -X PUT
> ".../webhdfs/v1/t1?op=CREATE&user.name=<userName>&overwrite=false"
> ...
> {"RemoteException":{"exception":"IllegalArgumentException","javaClassName":"java.lang.IllegalArgumentException","message":"n
> must be positive"}}
> Need to fix the report to give user hint about dead datanode.
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