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https://issues.apache.org/jira/browse/HDFS-10999?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15602650#comment-15602650
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Allen Wittenauer commented on HDFS-10999:
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I've been out of town and I've had more time to think about this issue.
I'm pretty much convinced that tying what are effectively two metrics to a
single value is a bad idea. I would really want to see the two values
separated because it does directly impact how maintenance windows and recovery
are performed. More information is significantly more valuable than less here.
The same goes for other metrics such as rates: I really do want to know how
long it is taking for full blocks to replicate vs. EC blocks to recovery. They
have slightly different performance characteristics at the node level and
advanced users are going to want to know what the perf impact on any runnings
jobs might be.
For example, if I know my nodes take x% of the CPU for EC recovery during a
node migration, I'm going to want to set the CPU settings for the Docker
cgroups that I'm using to protect my cluster from YARN's security issues
differently during that migration to make sure I have enough juice vs. normal
operation.
In other words, this is not a good place to 'dumb down' the metrics.
> Use more generic "low redundancy" blocks instead of "under replicated" blocks
> -----------------------------------------------------------------------------
>
> Key: HDFS-10999
> URL: https://issues.apache.org/jira/browse/HDFS-10999
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: erasure-coding
> Affects Versions: 3.0.0-alpha1
> Reporter: Wei-Chiu Chuang
> Assignee: Yuanbo Liu
> Labels: supportability
>
> Per HDFS-9857, it seems in the Hadoop 3 world, people prefer the more generic
> term "low redundancy" to the old-fashioned "under replicated". But this term
> is still being used in messages in several places, such as web ui, dfsadmin
> and fsck. We should probably change them to avoid confusion.
> File this jira to discuss it.
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