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From "Hudson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-5399) Revisit SafeModeException and corresponding retry policies
Date Wed, 05 Feb 2014 04:34:09 GMT

    [ https://issues.apache.org/jira/browse/HDFS-5399?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13891700#comment-13891700
] 

Hudson commented on HDFS-5399:
------------------------------

SUCCESS: Integrated in Hadoop-trunk-Commit #5106 (See [https://builds.apache.org/job/Hadoop-trunk-Commit/5106/])
Correct CHANGES.txt entry for HDFS-5399 (contributed by Jing, not Haohui) (todd: http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1564632)
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
HDFS-5399. Revisit SafeModeException and corresponding retry policies. Contributed by Haohui
Mai. (todd: http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1564629)
* /hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/retry/RetryPolicies.java
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSClient.java
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/NameNodeProxies.java
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/WebHdfsFileSystem.java
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestHASafeMode.java


> Revisit SafeModeException and corresponding retry policies
> ----------------------------------------------------------
>
>                 Key: HDFS-5399
>                 URL: https://issues.apache.org/jira/browse/HDFS-5399
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>    Affects Versions: 2.3.0
>            Reporter: Jing Zhao
>            Assignee: Jing Zhao
>             Fix For: 2.3.0
>
>         Attachments: HDFS-5399.000.patch, HDFS-5399.001.patch, HDFS-5399.003.patch, hdfs-5399.002.patch
>
>
> Currently for NN SafeMode, we have the following corresponding retry policies:
> # In non-HA setup, for certain API call ("create"), the client will retry if the NN is
in SafeMode. Specifically, the client side's RPC adopts MultipleLinearRandomRetry policy for
a wrapped SafeModeException when retry is enabled.
> # In HA setup, the client will retry if the NN is Active and in SafeMode. Specifically,
the SafeModeException is wrapped as a RetriableException in the server side. Client side's
RPC uses FailoverOnNetworkExceptionRetry policy which recognizes RetriableException (see HDFS-5291).
> There are several possible issues in the current implementation:
> # The NN SafeMode can be a "Manual" SafeMode (i.e., started by administrator through
CLI), and the clients may not want to retry on this type of SafeMode.
> # Client may want to retry on other API calls in non-HA setup.
> # We should have a single generic strategy to address the mapping between SafeMode and
retry policy for both HA and non-HA setup. A possible straightforward solution is to always
wrap the SafeModeException in the RetriableException to indicate that the clients should retry.



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