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https://issues.apache.org/jira/browse/HDFS-3702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13422372#comment-13422372
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nkeywal commented on HDFS-3702:
-------------------------------

For a file open in writing, we will start with a call to ipc.Client to get the 
last block length. The timeout in hdfs 1.0.3 is harcoded to 20s (fixed in 
HADOOP-7397). Hence, anyway, HDFS-3704, but we can also hit HDFS-3701 at this 
point, so it also a question of data loss. That's why we need to fix (HDFS-3701 
and (HDFS-3702 or/and HDFS-3705 or/and HDFS-3703)).

For reducing the connect timeout, are you speaking about dfs.socket.timeout? Is 
there a way to change it for connect timeout only?

                
> Add an option for NOT writing the blocks locally if there is a datanode on 
> the same box as the client
> -----------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-3702
>                 URL: https://issues.apache.org/jira/browse/HDFS-3702
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: hdfs client
>    Affects Versions: 1.0.3, 2.0.0-alpha
>            Reporter: nkeywal
>            Priority: Minor
>
> This is useful for Write-Ahead-Logs: these files are writen for recovery 
> only, and are not read when there are no failures.
> Taking HBase as an example, these files will be read only if the process that 
> wrote them (the 'HBase regionserver') dies. This will likely come from a 
> hardware failure, hence the corresponding datanode will be dead as well. So 
> we're writing 3 replicas, but in reality only 2 of them are really useful.

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