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https://issues.apache.org/jira/browse/HDFS-8320?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14549656#comment-14549656
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Jing Zhao commented on HDFS-8320:
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Thanks for updating the patch, Zhe! The new patch looks pretty good to me. Only
one comment, in {{getStartOffsetsForInternalBlocks}}, the start offset for
parity blocks can be smaller than the start offset of the first data block.
Here I think we can set it to the smallest offset among all the data blocks.
{code}
+ for (int i = dataBlkNum; i < dataBlkNum + parityBlkNum; i++) {
+ startOffsets[i] = startOffsets[0];
+ }
{code}
> Erasure coding: consolidate striping-related terminologies
> ----------------------------------------------------------
>
> Key: HDFS-8320
> URL: https://issues.apache.org/jira/browse/HDFS-8320
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Zhe Zhang
> Assignee: Zhe Zhang
> Attachments: HDFS-8320-HDFS-7285.00.patch,
> HDFS-8320-HDFS-7285.01.patch
>
>
> Right now we are doing striping-based I/O in a number of places:
> # Client output stream (HDFS-7889)
> # Client input stream
> #* pread (HDFS-7782, HDFS-7678)
> #* stateful read (HDFS-8033, HDFS-8281, HDFS-8319)
> # DN reconstruction (HDFS-7348)
> In each place we use one or multiple of the following terminologies:
> # Cell
> # Stripe
> # Block group
> # Internal block
> # Chunk
> This JIRA aims to systematically define these terminologies in relation with
> each other and in the context of the containing file. For example, a cell
> belong to stripe _i_ and internal block _j_ can be indexed as {{(i, j)}} and
> its logical index _k_ in the file can be calculated.
> With the above consolidation, hopefully we can further consolidate striping
> I/O codes.
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