[jira] Updated: (HADOOP-109) Blocks are not replicated when...

["Sameer Paranjpye (JIRA)" <ji...@apache.org>]

     [ http://issues.apache.org/jira/browse/HADOOP-109?page=all ]

Sameer Paranjpye updated HADOOP-109:
------------------------------------

      Version: 0.1.0
    Assign To: Konstantin Shvachko

> Blocks are not replicated when...
> ---------------------------------
>
>          Key: HADOOP-109
>          URL: http://issues.apache.org/jira/browse/HADOOP-109
>      Project: Hadoop
>         Type: Bug

>   Components: dfs
>     Versions: 0.1.0
>     Reporter: Konstantin Shvachko
>     Assignee: Konstantin Shvachko
>      Fix For: 0.3

>
> When the block is under-replicated the namenode places it into
> FSNamesystem.neededReplications list.
> When a datanode D1 sends getBlockwork() request to the namenode, the namenode
> selects another node D2 (which it thinks is up and running) where the new replica of the
> under-replicated block will be stored.
> Then namenode removes the block from the neededReplications list and places it to
> the pendingReplications list, and then asks D1 to replicate the block to D2.
> If D2 is in fact down, then replication will fail and will never be retried later, because
> the block is not in the neededReplications list, but rather in the pendingReplications list,
> which namenode never checks.

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