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From "Zhe Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-7716) Erasure Coding: extend BlockInfo to handle EC info
Date Thu, 05 Feb 2015 07:00:50 GMT

    [ https://issues.apache.org/jira/browse/HDFS-7716?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14306764#comment-14306764
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Zhe Zhang commented on HDFS-7716:
---------------------------------

Thanks Jing! The high-level plan looks good. Below are some detailed items we can further
discuss:
# Shall we use {{triplets}} to record block locations in an block group?
# If we use {{triplets}} for both replicated blocks and EC block groups, I don't clearly see
which fields and methods to offload to {{BlockReplicationInfo}}. Thoughts?
# We discussed recording the EC schema in {{BlockGroupInfo}} to avoid frequently checking
INode. Before HDFS-7337 we can simply record the number of data and parity blocks (2 {{short}}
variables). 
# An INode feature for {{BlockGroupInfo}} sounds good. Before our meetup last week, HDFS-7339's
[patch | https://issues.apache.org/jira/secure/attachment/12693731/HDFS-7339-006.patch] used
that approach. We might be able to reuse some code.
# [~andrew.wang] and I have discussed how to support snapshots when a file is converted between
replicated and EC forms. If we keep both the regular {{BlockInfo}} array and the {{BlockGroupInfo}}
feature, we should be able to calculate snapshots.

> Erasure Coding: extend BlockInfo to handle EC info
> --------------------------------------------------
>
>                 Key: HDFS-7716
>                 URL: https://issues.apache.org/jira/browse/HDFS-7716
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>            Reporter: Jing Zhao
>            Assignee: Jing Zhao
>
> The current BlockInfo's implementation only supports the replication mechanism. To use
the same blocksMap handling block group and its data/parity blocks, we need to define a new
BlockGroupInfo class.



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