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From "Walter Su (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-9918) Erasure Coding: Sort located striped blocks based on decommissioned states
Date Tue, 29 Mar 2016 10:09:25 GMT

    [ https://issues.apache.org/jira/browse/HDFS-9918?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15215796#comment-15215796
] 

Walter Su commented on HDFS-9918:
---------------------------------

We also need to sort locations by distance. It's unlikely but from 2 duplicated in-service
blocks we want to choose the nearer one. The logic is like {{sortLocatedBlocks(..)}}, how
about reuse it?
We move {{BlockIndex}} & {{BlockToken}} according to {{Location}}. Like
{code}
//public void sortLocatedBlocks(final String targethost,
     for (LocatedBlock b : locatedblocks) {
       DatanodeInfo[] di = b.getLocations();
+      HashMap<DatanodeInfo, Byte> locToIndex = null;
+      HashMap<DatanodeInfo, Token<BlockTokenIdentifier>> locToToken = null;
+      if(b instanceof LocatedStripedBlock){
+        locToIndex = new HashMap<>();
+        locToToken = new HashMap<>();
+        LocatedStripedBlock lb = (LocatedStripedBlock) b;
+        for(int i=0; i<di.length; i++){
+          locToIndex.put(di[i], lb.getBlockIndices()[i]);
+          locToToken.put(di[i], lb.getBlockTokens()[i]);
+        }
+      }
       // Move decommissioned/stale datanodes to the bottom
...
       networktopology.sortByDistance(client, b.getLocations(), activeLen);
       // must update cache since we modified locations array
       b.updateCachedStorageInfo();
+
+      if(b instanceof  LocatedStripedBlock){
+        LocatedStripedBlock lb = (LocatedStripedBlock) b;
+        for(int i =0 ;i<di.length;i++){
+          lb.getBlockIndices()[i] = locToIndex.get(di[i]);
+          lb.getBlockTokens()[i] = locToToken.get(di[i]);
+        }
+      }
{code}
It passes your tests.

> 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
>
>
> 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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