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From "Michael Ridley (JIRA)" <>
Subject [jira] [Commented] (ACCUMULO-884) Insight into short circuit read for local files
Date Sat, 14 Feb 2015 17:45:16 GMT


Michael Ridley commented on ACCUMULO-884:

I have done some benchmarking recently to compare Accumulo performance with HDFS short circuit
local reads enabled versus not.  I expect we will be publishing the results some time in the
next few months.  By April at the latest.  But for some workloads it definitely improves performance

> Insight into short circuit read for local files
> -----------------------------------------------
>                 Key: ACCUMULO-884
>                 URL:
>             Project: Accumulo
>          Issue Type: Sub-task
>          Components: docs
>            Reporter: Billie Rinaldi
> This is a new feature in hadoop 1.0.x and some versions of 0.22 and 0.23.  It allows
a client to read directly from disk instead of through a DataNode when the data is stored
locally.  Enabling it involves setting two configuration parameters, the first in hdfs-site.xml
and the second in accumulo-site.xml.  We should make sure this works with Accumulo and recommend
it in the documentation.
> - dfs.block.local-path-access.user is the key in datanode configuration to specify the
user allowed to do short circuit read.
> - is the key to enable short circuit read at the client
side configuration.
> See HDFS-2246 and for more information.

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