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https://issues.apache.org/jira/browse/HDFS-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13109117#comment-13109117
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Todd Lipcon commented on HDFS-2246:
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bq. Since both the client and HDFS are running as the same user, this mechanism
will work fine
Could you explain that? I imagine the more likely deployment is that the client
is running as 'hbase' and the DN is running as 'hdfs'. Then they would share a
common group and have block files chmodded g+r.
bq. The ClientDatanodeProtocol RPC proxy is created using block token. This
means an RPC proxy is created for every block. This robs the performance gain
from the patch.
With the path cache, why's this true? It seems that, so long as you're
accessing a relatively bounded number of blocks, the paths will all be cached
and you won't need to re-RPC unless a block moves, etc?
> Shortcut a local client reads to a Datanodes files directly
> -----------------------------------------------------------
>
> Key: HDFS-2246
> URL: https://issues.apache.org/jira/browse/HDFS-2246
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Sanjay Radia
> Attachments: 0001-HDFS-347.-Local-reads.patch, HDFS-2246.20s.1.patch,
> HDFS-2246.20s.2.txt, HDFS-2246.20s.3.txt, HDFS-2246.20s.patch,
> localReadShortcut20-security.2patch
>
>
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