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https://issues.apache.org/jira/browse/HDFS-14631?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16884709#comment-16884709
 ] 

He Xiaoqiao commented on HDFS-14631:
------------------------------------

[~LiJinglun], Thanks for report and patch this issue. Some review comments from 
me:
1. we should replace {{hasSubdirs}} with {{true}} since it is always 'true'.
{code:java}
+      if (idToBlockDir.equals(dir)) {
+        return new ReplicaDirInfo(currentDir.getAbsolutePath(), hasSubdirs);
+      }
{code}
2. It is better to use a random block id to verify the logic.
{code:java}
+    long blkId = 7600037L;
{code}
3. It seems {{Exception}} is never thrown in the following method.
{code:java}
  public void testLocalReplicaParsing() throws Exception {
    ...
  }
{code}
4. It should be better to add annotation for new unit test.

> The DirectoryScanner doesn't fix the wrongly placed replica.
> ------------------------------------------------------------
>
>                 Key: HDFS-14631
>                 URL: https://issues.apache.org/jira/browse/HDFS-14631
>             Project: Hadoop HDFS
>          Issue Type: Bug
>            Reporter: Jinglun
>            Assignee: Jinglun
>            Priority: Major
>         Attachments: HDFS-14631.001.patch
>
>
> When DirectoryScanner scans block files, if the block refers to the block 
> file does not exist the DirectoryScanner will update the block based on the 
> replica file found on the disk. See FsDatasetImpl#checkAndUpdate.
>  
> {code:java}
> /*
> * Block exists in volumeMap and the block file exists on the disk
> */
> // Compare block files
> if (memBlockInfo.blockDataExists()) {
>   ...
> } else {
>   // Block refers to a block file that does not exist.
>   // Update the block with the file found on the disk. Since the block
>   // file and metadata file are found as a pair on the disk, update
>   // the block based on the metadata file found on the disk
>   LOG.warn("Block file in replica "
>       + memBlockInfo.getBlockURI()
>       + " does not exist. Updating it to the file found during scan "
>       + diskFile.getAbsolutePath());
>   memBlockInfo.updateWithReplica(
>   StorageLocation.parse(diskFile.toString()));
>   LOG.warn("Updating generation stamp for block " + blockId
>       + " from " + memBlockInfo.getGenerationStamp() + " to " + diskGS);
>   memBlockInfo.setGenerationStamp(diskGS);
> }
> {code}
> But the DirectoryScanner doesn't really fix it because in 
> LocalReplica#parseBaseDir() the 'subdir' are ignored.
>  
>  



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