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https://issues.apache.org/jira/browse/HDFS-9918?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15226715#comment-15226715
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Rakesh R commented on HDFS-9918:
--------------------------------
Thanks a lot [~zhz], [~walter.k.su] for your time and kind advice. It would be
good if we could reach to an agreement.
{code}
0, 1, 2, 3, 4, 5, 6, 7, 8, 1, 0', 1', 7', 8'
{code}
bq. In the v8 patch, I think we can use a DECOM_COMPARATOR-based sort on each
list in blkIndex2LocationsMap
I've used {{DecomStaleComparator}} in v8 patch, here it moves both decommn and
stale nodes to bottom. Does this makes sense?.
{code}
+ // 1. Move stale datanodes to the bottom
+ if (!decommissioned && avoidStaleDataNodesForRead) {
+ Collections.sort(dns, new DFSUtil.DecomStaleComparator(staleInterval));
+ }
{code}
bq. Then for the first numDataUnits slots in the result, we take the first
location from the index.
OK, I will update the patch accordingly once we agree upon final solution.
> Erasure Coding: Sort located striped blocks based on decommissioned states
> --------------------------------------------------------------------------
>
> Key: HDFS-9918
> URL: https://issues.apache.org/jira/browse/HDFS-9918
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Rakesh R
> Assignee: Rakesh R
> Attachments: HDFS-9918-001.patch, HDFS-9918-002.patch,
> HDFS-9918-003.patch, HDFS-9918-004.patch, HDFS-9918-005.patch,
> HDFS-9918-006.patch, HDFS-9918-007.patch, HDFS-9918-008.patch
>
>
> This jira is a follow-on work of HDFS-8786, where we do decommissioning of
> datanodes having striped blocks.
> Now, after decommissioning it requires to change the ordering of the storage
> list so that the decommissioned datanodes should only be last node in list.
> For example, assume we have a block group with storage list:-
> d0, d1, d2, d3, d4, d5, d6, d7, d8, d9
> mapping to indices
> 0, 1, 2, 3, 4, 5, 6, 7, 8, 2
> Here the internal block b2 is duplicated, locating in d2 and d9. If d2 is a
> decommissioning node then should switch d2 and d9 in the storage list.
> Thanks [~jingzhao] for the
> [discussions|https://issues.apache.org/jira/browse/HDFS-8786?focusedCommentId=15180415&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15180415]
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