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https://issues.apache.org/jira/browse/HDFS-6441?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14010250#comment-14010250
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Benoy Antony commented on HDFS-6441:
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{quote}
What happens if neither option is given? It appears to maybe ignore all hosts?
{quote}
If neither option is given, all the nodes will be included. This is the
behavior without this patch.
The internal boolean variable (exclude) is set to true, but the list of nodes
to exclude will be empty.
{quote}
If both options are given, it appears to build a union of the include/exclude
hosts, then use the last argument to determine if the union is exclude or not?
{quote}
If both options are given, the last option will be effective.
{quote}
I seem to recall getHostName is (or used to be) a bit peculiar and can return a
DN self-reported name, hence the getPeerHostName which is guaranteed to return
the actual hostname. You should check and match the NN's behavior on use of
peer name or reported name.
{quote}
I believe, You are right. I'll check and test with _getPeerHostName_
{quote}
_DEFALUT is misspelled
{quote}
I'll fix this.
> Add ability to exclude/include few datanodes while balancing
> ------------------------------------------------------------
>
> Key: HDFS-6441
> URL: https://issues.apache.org/jira/browse/HDFS-6441
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: balancer
> Affects Versions: 2.4.0
> Reporter: Benoy Antony
> Assignee: Benoy Antony
> Attachments: HDFS-6441.patch, HDFS-6441.patch, HDFS-6441.patch,
> HDFS-6441.patch, HDFS-6441.patch, HDFS-6441.patch, HDFS-6441.patch,
> HDFS-6441.patch, HDFS-6441.patch
>
>
> In some use cases, it is desirable to ignore a few data nodes while
> balancing. The administrator should be able to specify a list of data nodes
> in a file similar to the hosts file and the balancer should ignore these data
> nodes while balancing so that no blocks are added/removed on these nodes.
> Similarly it will be beneficial to specify that only a particular list of
> datanodes should be considered for balancing.
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