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https://issues.apache.org/jira/browse/HDFS-17794?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18041616#comment-18041616
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ASF GitHub Bot commented on HDFS-17794:
---------------------------------------
Jimvin commented on code in PR #8065:
URL: https://github.com/apache/hadoop/pull/8065#discussion_r2573539694
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hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml:
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@@ -1779,6 +1779,21 @@
</description>
</property>
+<property>
+ <name>dfs.datanode.synconclose</name>
+ <value>false</value>
+ <description>
+ If this configuration is enabled, the datanode will instruct the
+ operating system to sync data block files contents to disk when the
+ blockfile is closed.
+
+ This has the benefit of ensuring that data is written to disk
+ immediately when a block is closed, avoiding the data being held
+ in the operating system cache. This can help data loss in the event
+ of a malfunction such as a power failure.
Review Comment:
I've added the word "avoiding the data being held solely in the operating
system cache" in the description to clarify the behaviour. You're correct that
it does not remove the block from the operating system cache, this should make
the description clearer.
> Document the property dfs.datanode.synconclose
> ----------------------------------------------
>
> Key: HDFS-17794
> URL: https://issues.apache.org/jira/browse/HDFS-17794
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: documentation
> Affects Versions: 3.4.1
> Reporter: Jim Halfpenny
> Assignee: Jim Halfpenny
> Priority: Minor
> Labels: pull-request-available
>
> The hdfs-site.xml property dfs.datanode.synconclose appears in the HDFS code
> but is not documented. The property, it's default value and the behaviour of
> this configuration property should be added to the Hadoop HDFS documentation.
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