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From "Zhe Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-8058) Erasure coding: use BlockInfo[] for both striped and contiguous blocks in INodeFile
Date Mon, 06 Apr 2015 23:13:13 GMT

    [ https://issues.apache.org/jira/browse/HDFS-8058?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14482164#comment-14482164
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Zhe Zhang commented on HDFS-8058:
---------------------------------

Thanks for the work Yi! The overall approach looks fine to me.

The only concern I can think of is type safety:  on the surface, a generic {{BlockInfo[]}}
could contain mixed types.. We need some extra logic to prevent a striped block to be added
to a non-striped file, and vice versa.

We also _might_ need to maintain both striped and contiguous blocks of a file during the window
of conversion (that part of design is not finalized yet).

> Erasure coding: use BlockInfo[] for both striped and contiguous blocks in INodeFile
> -----------------------------------------------------------------------------------
>
>                 Key: HDFS-8058
>                 URL: https://issues.apache.org/jira/browse/HDFS-8058
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>    Affects Versions: HDFS-7285
>            Reporter: Yi Liu
>            Assignee: Yi Liu
>         Attachments: HDFS-8058.001.patch, HDFS-8058.002.patch
>
>
> This JIRA is to use {{BlockInfo[] blocks}} for both striped and contiguous blocks in
INodeFile.
> Currently {{FileWithStripedBlocksFeature}} keeps separate list for striped blocks, and
the methods there duplicate with those in INodeFile, and current code need to judge {{isStriped}}
then do different things. Also if file is striped, the {{blocks}} in INodeFile occupy a reference
memory space.
> These are not necessary, and we can use the same {{blocks}} to make code more clear.
> I keep {{FileWithStripedBlocksFeature}} as empty for follow use: I will file a new JIRA
to move {{dataBlockNum}} and {{parityBlockNum}} from *BlockInfoStriped* to INodeFile, since
ideally they are the same for all striped blocks in a file, and store them in block will waste
NN memory.



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