Bharat Viswanadham created HDFS-13356:
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Summary: Balancer:Set default value of minBlockSize to 10mb
Key: HDFS-13356
URL: https://issues.apache.org/jira/browse/HDFS-13356
Project: Hadoop HDFS
Issue Type: Bug
Reporter: Bharat Viswanadham
Assignee: Bharat Viswanadham
It seems we can run into a problem while a rolling upgrade with this.
The Balancer is upgraded after NameNodes, so once NN is upgraded it will expect
{{minBlockSize}}parameter in {{getBlocks()}}. The Balancer cannot send it yet,
so NN will use the default, which you set to 0. So NN will start unexpectedly
sending small blocks to the Balancer. So we should
# either change the default in protobuf to 10 MB
# or treat {{minBlockSize == 0}} in {{NameNodeRpcServer}} as a signal to use
the configuration variable
{{DFSConfigKeys.DFS_BALANCER_GETBLOCKS_MIN_BLOCK_SIZE_KEY}}.
If you agree, we should create a follow up jira. I wanted to backport this down
the chain of branches, but this upgrade scenario is stopping me.
[~barnaul] commented this in HDFS-13222 jira.
https://issues.apache.org/jira/browse/HDFS-13222?focusedCommentId=16414855&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-16414855
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