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From "Yanbo Liang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-3734) TestFSEditLogLoader.testReplicationAdjusted() will hang if number of blocks are more than one
Date Wed, 01 Aug 2012 08:49:34 GMT

    [ https://issues.apache.org/jira/browse/HDFS-3734?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13426382#comment-13426382
] 

Yanbo Liang commented on HDFS-3734:
-----------------------------------

I just run and analysis the test case. I found that other reason caused this test case failure
if number of blocks before cluster restart are more than one. It because that the MiniDFSCluster
used by this case only have two DataNodes in the test source code. According to the BlockPlacementPolicy,
if the total DataNode numbers of the cluster is less than the min replication, the real replication
will equal to the smaller one(in this case is the total DataNode numbers).

So if you just modified the min replication to 3 and the total number of DataNode is still
2, then the real replication will still 2.
Modify the test scenario
------------------------
1. Modify the number of DataNode in MiniDFSCluster to 3.
2. Write a file with min replication as 2 and replication factor as 2.
3. Change the min replication to 3 and restart the cluster. 
------------------------
Then the test case will pass as expected.
So I support this jira is not a bug. 
                
> TestFSEditLogLoader.testReplicationAdjusted() will hang if number of blocks are more
than one
> ---------------------------------------------------------------------------------------------
>
>                 Key: HDFS-3734
>                 URL: https://issues.apache.org/jira/browse/HDFS-3734
>             Project: Hadoop HDFS
>          Issue Type: Bug
>    Affects Versions: 2.1.0-alpha, 3.0.0
>            Reporter: Vinay
>
> TestFSEditLogLoader.testReplicationAdjusted() which was added in HDFS-2003 will fail
if number of blocks before cluster restart are more than one.
> Test Scenario:
> --------------
> 1. Write a file with min replication as 1 and replication factor as 1.
> 2. Change the min replication to 2 and restart the cluster.
> Expected: Min replication should be automatically reset on cluster restart by replicating
more blocks.
> Currently, if the number of blocks before restart is only one, then on restart NN will
not enter safemode, hence replication will happen and satisfies min replication factor.
> If initial blocks count is more than 1 which are having replication factor as 1, then
on restart NN will enter safemode and will never come out.

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