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https://issues.apache.org/jira/browse/HDFS-8833?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14726718#comment-14726718
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Rakesh R commented on HDFS-8833:
--------------------------------
Great!
IMHO, it would be good to summarize the discussion to understand more about the
agreed semantics(like [~jingzhao] mentioned earlier), I'm trying an attempt
here. Please correct me if I miss anything.
- rename a path -> allows rename a path to a different EC policy
- non-empty dir -> allows setting EC policy to a non-empty dir
- on a file -> not allows to set EC policy on a file
- dir already has a policy -> not allows to set EC policy again to this dir
- EC PolicyID -> 0 represents no EC policy, 1 represents default policy. Will
support more policies later.
Overall changes looks fine to me. Please modify {{EC zone}} to {{EC policy}}
when committing it.
{code}
} catch (IOException e) {
blockLog
.warn("Failed to get the EC zone for the file {} ", src);
}
{code}
> Erasure coding: store EC schema and cell size in INodeFile and eliminate
> notion of EC zones
> -------------------------------------------------------------------------------------------
>
> Key: HDFS-8833
> URL: https://issues.apache.org/jira/browse/HDFS-8833
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: namenode
> Affects Versions: HDFS-7285
> Reporter: Zhe Zhang
> Assignee: Zhe Zhang
> Attachments: HDFS-8833-HDFS-7285-merge.00.patch,
> HDFS-8833-HDFS-7285-merge.01.patch, HDFS-8833-HDFS-7285.02.patch,
> HDFS-8833-HDFS-7285.03.patch, HDFS-8833-HDFS-7285.04.patch
>
>
> We have [discussed |
> https://issues.apache.org/jira/browse/HDFS-7285?focusedCommentId=14357754&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14357754]
> storing EC schema with files instead of EC zones and recently revisited the
> discussion under HDFS-8059.
> As a recap, the _zone_ concept has severe limitations including renaming and
> nested configuration. Those limitations are valid in encryption for security
> reasons and it doesn't make sense to carry them over in EC.
> This JIRA aims to store EC schema and cell size on {{INodeFile}} level. For
> simplicity, we should first implement it as an xattr and consider memory
> optimizations (such as moving it to file header) as a follow-on. We should
> also disable changing EC policy on a non-empty file / dir in the first phase.
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