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https://issues.apache.org/jira/browse/HDFS-6808?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14120477#comment-14120477
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Colin Patrick McCabe commented on HDFS-6808:
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* This patch seems to be reserving {{hdfs dfsadmin \-reload 127.0.0.1:8020}}
for reloading just datanode configurations. If we plan on making more daemons
reconfigurable in the future, we'll want to alter this command to something
like {{hdfs dfsadmin \-reload \-datanode 127.0.0.1:8020}} (so that we can have
a {{\-namenode}} or {{\-journalnode}} version at some point in the future).
* The new RPC currently has no return value. But we need to have some way to
reporting back information about which configuration keys were successfully
reloaded and which were not. I believe HADOOP-7001 supplies all this
information. Let's expose it in the RPC and in the shell.
{code}
+ for (ReconfigurationUtil.PropertyChange change : changes) {
+ if (!isPropertyReconfigurable(change.prop)) {
+ LOG.info("Property " + change.prop + " is not reconfigurable.");
+ continue;
+ }
+ LOG.info("Change property: " + change.prop + " from \""
+ + change.oldVal == null ? "<default>" : change.oldVal
+ + "\" to \"" + change.newVal == null ? "<default>" : change.newVal
+ + "\".");
+ try {
+ reconfigurePropertyImpl(change.prop, change.newVal);
+ } catch (ReconfigurationException e) {
+ throw new IOException(e);
+ }
+ }
{code}
On the first exception we get, we immediately stop reapplying the
configuration. This seems brittle. Instead, we should remember all the
exceptions but continue applying changes we can apply. Then we should report
the failures back to the user as described...
> Add command line option to ask DataNode reload configuration.
> -------------------------------------------------------------
>
> Key: HDFS-6808
> URL: https://issues.apache.org/jira/browse/HDFS-6808
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: datanode
> Affects Versions: 2.5.0
> Reporter: Lei (Eddy) Xu
> Assignee: Lei (Eddy) Xu
> Attachments: HDFS-6808.000.combo.patch, HDFS-6808.000.patch
>
>
> The workflow of dynamically changing data volumes on DataNode is
> # Users manually changed {{dfs.datanode.data.dir}} in the configuration file
> # User use command line to notify DN to reload configuration and updates its
> volumes.
> This work adds command line support to notify DN to reload configuration.
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