[
https://issues.apache.org/jira/browse/HDFS-8833?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14698978#comment-14698978
]
Jing Zhao commented on HDFS-8833:
---------------------------------
Thanks for the patch, Zhe!
bq. to allow setErasureCodingPolicy on non-empty directories
To me allowing setting erasure coding policy on non-empty directories may not
be a good idea. The semantic here means newly created files will be erasure
coded, but old files are unchanged. This is inconsistent with the existing
storage policy semantic, where later old files are supposed to be moved by
tools like Mover thus the policy is enforced on both the old and the new files.
Even though the ec policy and the storage policy are two different things, the
end users may still be very confused about these two different types of
semantic.
> 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
>
>
> 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.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
