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https://issues.apache.org/jira/browse/HDFS-14578?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17071361#comment-17071361
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Wei-Chiu Chuang commented on HDFS-14578:
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[~ayushtkn] I honestly don't understand what this patch does (as stated in
hdfs-default.xml) without looking at the code.
{quote}
Only used when the dfs.block.replicator.classname is set to
org.apache.hadoop.hdfs.server.blockmanagement.AvailableSpaceBlockPlacementPolicy.
If true, balances the local node too.
{quote}
Am I correct to assume the local DataNode is chosen if the disk usage is below
50%?
> AvailableSpaceBlockPlacementPolicy always prefers local node
> ------------------------------------------------------------
>
> Key: HDFS-14578
> URL: https://issues.apache.org/jira/browse/HDFS-14578
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: block placement
> Affects Versions: 2.8.0, 2.7.4, 3.0.0-alpha1
> Reporter: Wei-Chiu Chuang
> Assignee: Ayush Saxena
> Priority: Major
> Fix For: 3.3.0, 3.1.4, 3.2.2
>
> Attachments: HDFS-14578-02.patch, HDFS-14578-03.patch,
> HDFS-14578-04.patch, HDFS-14578-05.patch, HDFS-14578-06.patch,
> HDFS-14578-07.patch, HDFS-14578-WIP-01.patch, HDFS-14758-01.patch
>
>
> It looks like AvailableSpaceBlockPlacementPolicy prefers local disk just like
> in the BlockPlacementPolicyDefault
>
> As Yongjun mentioned in
> [HDFS-8131|https://issues.apache.org/jira/browse/HDFS-8131?focusedCommentId=16558739&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-16558739],
>
> {quote}Class AvailableSpaceBlockPlacementPolicy extends
> BlockPlacementPolicyDefault. But it doesn't change the behavior of choosing
> the first node in BlockPlacementPolicyDefault, so even with this new feature,
> the local DN is always chosen as the first DN (of course when it is not
> excluded), and the new feature only changes the selection of the rest of the
> two DNs.
> {quote}
> I'm file this Jira as I groom Cloudera's internal Jira and found this
> unreported issue. We do have a customer hitting this problem. I don't have a
> fix, but thought it would be beneficial to report it to Apache Jira.
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