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https://issues.apache.org/jira/browse/HDFS-12534?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16178479#comment-16178479
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Huafeng Wang commented on HDFS-12534:
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Hi [~andrew.wang], I have a question here.
{quote}
Applications depend on HDFS BlockLocation to understand where the split points
are.
{quote}
I think currently the returned logical BlockLocation per block group has all
the data block and parity block's locations. Isn't these information enough?
What's the difference between splitting a single block group and multiple
logical block locations here?
> Provide logical BlockLocations for EC files for better split calculation
> ------------------------------------------------------------------------
>
> Key: HDFS-12534
> URL: https://issues.apache.org/jira/browse/HDFS-12534
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: erasure-coding
> Affects Versions: 3.0.0-beta1
> Reporter: Andrew Wang
> Labels: hdfs-ec-3.0-must-do
>
> I talked to [~vanzin] and [~alex.behm] some more about split calculation with
> EC. It turns out HDFS-12222 was resolved prematurely. Applications depend on
> HDFS BlockLocation to understand where the split points are. The current
> scheme of returning one BlockLocation per block group loses this information.
> We should change this to provide logical blocks. Divide the file length by
> the block size and provide suitable BlockLocations to match, with virtual
> offsets and lengths too.
> I'm not marking this as incompatible, since changing it this way would in
> fact make it more compatible from the perspective of applications that are
> scheduling against replicated files. Thus, it'd be good for beta1 if
> possible, but okay for later too.
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