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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Trivial Update of "FAQ" by GautamGopalakrishnan
Date Fri, 31 Jul 2015 04:08:49 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Hadoop Wiki" for change notification.

The "FAQ" page has been changed by GautamGopalakrishnan:
https://wiki.apache.org/hadoop/FAQ?action=diff&rev1=114&rev2=115

Comment:
Added sentence about HDFS-3447

  == What does the message "Operation category READ/WRITE is not supported in state standby"
mean? ==
  In an HA-enabled cluster, DFS clients cannot know in advance which namenode is active at
a given time. So when a client contacts a namenode and it happens to be the standby, the READ
or WRITE operation will be refused and this message is logged. The client will then automatically
contact the other namenode and try the operation again. As long as there is one active and
one standby namenode in the cluster, this message can be safely ignored.
  
- If an application is configured to contact only one namenode always, this message indicates
that the application is failing to perform any read/write operation. In such situations, the
application would need to be modified to use the HA configuration for the cluster.
+ If an application is configured to contact only one namenode always, this message indicates
that the application is failing to perform any read/write operation. In such situations, the
application would need to be modified to use the HA configuration for the cluster. The jira
[[https://issues.apache.org/jira/browse/HDFS-3447|HDFS-3447]] deals with lowering the severity
of this message (and similar ones) to DEBUG so as to reduce noise in the logs, but is unresolved
as of July 2015.
  
  = Platform Specific =
  == General ==

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