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Hadoop QA commented on HADOOP-5734: ----------------------------------- +1 overall. Here are the results of testing the latest attachment http://issues.apache.org/jira/secure/attachment/12406316/HADOOP-5734.patch against trunk revision 769174. +1 @author. The patch does not contain any @author tags. +0 tests included. The patch appears to be a documentation patch that doesn't require tests. +1 javadoc. The javadoc tool did not generate any warning messages. +1 javac. The applied patch does not increase the total number of javac compiler warnings. +1 findbugs. The patch does not introduce any new Findbugs warnings. +1 Eclipse classpath. The patch retains Eclipse classpath integrity. +1 release audit. The applied patch does not increase the total number of release audit warnings. +1 core tests. The patch passed core unit tests. +1 contrib tests. The patch passed contrib unit tests. Test results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch-vesta.apache.org/253/testReport/ Findbugs warnings: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch-vesta.apache.org/253/artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html Checkstyle results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch-vesta.apache.org/253/artifact/trunk/build/test/checkstyle-errors.html Console output: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch-vesta.apache.org/253/console This message is automatically generated. > HDFS architecture documentation describes outdated placement policy > ------------------------------------------------------------------- > > Key: HADOOP-5734 > URL: https://issues.apache.org/jira/browse/HADOOP-5734 > Project: Hadoop Core > Issue Type: Bug > Components: documentation > Affects Versions: 0.20.0 > Reporter: Konstantin Boudnik > Priority: Minor > Fix For: 0.21.0 > > Attachments: HADOOP-5734.patch > > > The "Replica Placement: The First Baby Steps" section of HDFS architecture > document states: > "... > For the common case, when the replication factor is three, HDFS's placement > policy is to put one replica on one node in the local rack, another on a > different node in the local rack, and the last on a different node in a > different rack. This policy cuts the inter-rack write traffic which generally > improves write performance. > ..." > However, according to the ReplicationTargetChooser.chooseTarger()'s code the > actual logic is to put the second replica on a different rack as well as the > third replica. So you have two replicas located on a different nodes of > remote rack and one (initial replica) on the local rack's node. Thus, the > sentence should say something like this: > "For the common case, when the replication factor is three, HDFS's placement > policy is to put one replica on one node in the local rack, another on a node > in a different (remote) rack, and the last on a different node in the same > remote rack. This policy cuts the inter-rack write traffic which generally > improves write performance." -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.