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https://issues.apache.org/jira/browse/HDFS-7300?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14187406#comment-14187406
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Hadoop QA commented on HDFS-7300:
---------------------------------
{color:red}-1 overall{color}. Here are the results of testing the latest
attachment
http://issues.apache.org/jira/secure/attachment/12677641/HDFS-7300.patch
against trunk revision ade3727.
{color:green}+1 @author{color}. The patch does not contain any @author
tags.
{color:red}-1 tests included{color}. The patch doesn't appear to include
any new or modified tests.
Please justify why no new tests are needed for this
patch.
Also please list what manual steps were performed to
verify this patch.
{color:green}+1 javac{color}. The applied patch does not increase the
total number of javac compiler warnings.
{color:green}+1 javadoc{color}. There were no new javadoc warning messages.
{color:green}+1 eclipse:eclipse{color}. The patch built with
eclipse:eclipse.
{color:green}+1 findbugs{color}. The patch does not introduce any new
Findbugs (version 2.0.3) warnings.
{color:green}+1 release audit{color}. The applied patch does not increase
the total number of release audit warnings.
{color:red}-1 core tests{color}. The patch failed these unit tests in
hadoop-hdfs-project/hadoop-hdfs:
org.apache.hadoop.hdfs.server.blockmanagement.TestBlockManager
org.apache.hadoop.hdfs.TestFileAppendRestart
The following test timeouts occurred in
hadoop-hdfs-project/hadoop-hdfs:
org.apache.hadoop.hdfs.TestFileCreation
{color:green}+1 contrib tests{color}. The patch passed contrib unit tests.
Test results:
https://builds.apache.org/job/PreCommit-HDFS-Build/8572//testReport/
Console output: https://builds.apache.org/job/PreCommit-HDFS-Build/8572//console
This message is automatically generated.
> The getMaxNodesPerRack() method in BlockPlacementPolicyDefault is flawed
> ------------------------------------------------------------------------
>
> Key: HDFS-7300
> URL: https://issues.apache.org/jira/browse/HDFS-7300
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Kihwal Lee
> Assignee: Kihwal Lee
> Priority: Critical
> Attachments: HDFS-7300.patch
>
>
> The {{getMaxNodesPerRack()}} can produce an undesirable result in some cases.
> - Three replicas on two racks. The max is 3, so everything can go to one rack.
> - Two replicas on two or more racks. The max is 2, both replicas can end up
> in the same rack.
> {{BlockManager#isNeededReplication()}} fixes this after block/file is closed
> because {{blockHasEnoughRacks()}} will return fail. This is not only extra
> work, but also can break the favored nodes feature.
> When there are two racks and two favored nodes are specified in the same
> rack, NN may allocate the third replica on a node in the same rack, because
> {{maxNodesPerRack}} is 3. When closing the file, NN moves a block to the
> other rack. There is 66% chance that a favored node is moved. If
> {{maxNodesPerRack}} was 2, this would not happen.
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