[jira] Issue Comment Edited: (HADOOP-1855) fsck should verify block placement

["Konstantin Shvachko (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-1855?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12534424 ] 

shv edited comment on HADOOP-1855 at 10/12/07 3:24 PM:
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Hairong, thanks for the comment. I updated the patch.
- I missed the case that when replication is 2 we gurantee that the two recplicas will be on two different racks.
- ReplicationTargetChooser.verifyBlockPlacement cannot use members of ReplicationTargetChooser because it is static.
- HashSet in general is more efficient for lookups, but has bigger space overhead than TreeSet. 
Since we expect mostly 2 elements in the set space is more important than time in this case imo.

      was (Author: shv):
    Hairong, thanks for the comment. I updated the patch.
I missed the case that when replication is 2 we gurantee that the two recplicas will be on two different racks.
  
> fsck should verify block placement
> ----------------------------------
>
>                 Key: HADOOP-1855
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1855
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: dfs
>    Affects Versions: 0.14.2
>            Reporter: dhruba borthakur
>            Assignee: Konstantin Shvachko
>             Fix For: 0.16.0
>
>         Attachments: FsckBlockPlacement1.patch
>
>
> fsck currently detects missing and under-replicated blocks. It would be helpful if it can also detect blocks that do not conform to the block placement policy. An administrator can use this tool to verify that blocks are distributed across racks.

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