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https://issues.apache.org/jira/browse/HDFS-11799?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16142981#comment-16142981
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Yongjun Zhang commented on HDFS-11799:
--------------------------------------
Sorry for the delay [~brahmareddy], here are my comments, largely cosmetic:
1. HdfsClientConfigKeys
1.1. String REPLICATION = PREFIX + "replication";
Need a better name than "replication", maybe "min-setup-replication"?
1.2 Change hdfs-default accordingly
2.DataStreamer
2.1 change
{code}
//check the minimal numbers nodes available to continue the wrtie.
{code}
to
{code}
// check the minimal number of nodes available to decide whether to
// continue the wrtie.
{code}
2.2 change
{code}
// threshold value, if yes continue writing to the two remaining nodes.
{code}
to
{code}
// threshold value, continue writing to the remaining nodes.
{code}
2.3 Change
{code}
+ " nodes since it's bigger than minimum replication: "
+ dfsClient.dtpReplaceDatanodeOnFailureReplication
+ " configued by "
{code}
to
{code}
+ " nodes since it's no less than minimum setup replication: "
+ dfsClient.dtpReplaceDatanodeOnFailureReplication
+ " configured by "
{code}
3. hdfs-default.xml
Suggest to change
"If this is set to 0 or a negative number, an exception will be thrown
when a replacement can not be found."
to
"If this is set to 0, an exception will be thrown, when a replacement
can not be found."
and the code accordingly. Not supporting negative number here seems less
confusing.
Thanks.
> Introduce a config to allow setting up write pipeline with fewer nodes than
> replication factor
> ----------------------------------------------------------------------------------------------
>
> Key: HDFS-11799
> URL: https://issues.apache.org/jira/browse/HDFS-11799
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Yongjun Zhang
> Assignee: Brahma Reddy Battula
> Attachments: HDFS-11799-002.patch, HDFS-11799-003.patch,
> HDFS-11799-004.patch, HDFS-11799.patch
>
>
> During pipeline recovery, if not enough DNs can be found, if
> dfs.client.block.write.replace-datanode-on-failure.best-effort
> is enabled, we let the pipeline to continue, even if there is a single DN.
> Similarly, when we create the write pipeline initially, if for some reason we
> can't find enough DNs, we can have a similar config to enable writing with a
> single DN.
> More study will be done.
>
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