[ACCUMULO-884] Insight into short circuit read for local files

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Abandoned
• Component/s: docs
• Assignee: Unassigned
• Reporter: Billie Rinaldi
• Created: 28/Nov/12 18:37
• Updated: 28/Oct/20 23:17
• Resolved: 28/Oct/20 23:17

Description

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.
• dfs.client.read.shortcircuit is the key to enable short circuit read at the client side configuration.

See HDFS-2246 and http://hbase.apache.org/book/perf.hdfs.configs.html for more information.

Issue Links

• depends upon: HDFS-347 DFS read performance suboptimal when client co-located on nodes with data