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Date: Mon, 31 Aug 2015 07:15:47 +0000 (UTC)
From: "Zhe Zhang (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: <JIRA.12849790.1438125336000.208649.1441005347132@Atlassian.JIRA>
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 <JIRA.12849790.1438125336128@arcas>
Subject: [jira] [Commented] (HDFS-8833) Erasure coding: store EC schema and
 cell size in INodeFile and eliminate notion of EC zones
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    [ https://issues.apache.org/jira/browse/HDFS-8833?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14723063#comment-14723063 ] 

Zhe Zhang commented on HDFS-8833:
---------------------------------

Thanks Walter for the feedback. Based on the above I think we have basically reached a consensus; the only pending issue is non-empty dir policy. Could you review the patch except for that part?

[~jingzhao] Could you take a look at the above comments from Andrew and Walter about non-empty dir policy?

> 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
>
>
> 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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