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https://issues.apache.org/jira/browse/HDFS-6482?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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James Thomas updated HDFS-6482:
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Release Note: The directory structure for finalized replicas on DNs has
been changed. Now, the directory that a finalized replica goes in is determined
uniquely by its ID. Specifically, we use a two-level directory structure, with
the 24th through 17th bits identifying the correct directory at the first level
and the 16th through 8th bits identifying the correct directory at the second
level. (was: The directory structure for finalized replicas on DNs has been
changed. Now, the directory that a finalized replica goes in is determined
uniquely by its ID. Specifically, we use a three-level directory structure,
with the 32nd through 25th bits of a block ID identifying the correct directory
at the first level, the 24th through 17th bits identifying the correct
directory at the second level, and the 16th through 8th identifying the correct
directory at the third level.)
> Use block ID-based block layout on datanodes
> --------------------------------------------
>
> Key: HDFS-6482
> URL: https://issues.apache.org/jira/browse/HDFS-6482
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: datanode
> Affects Versions: 2.5.0
> Reporter: James Thomas
> Assignee: James Thomas
> Attachments: HDFS-6482.1.patch, HDFS-6482.2.patch, HDFS-6482.3.patch,
> HDFS-6482.4.patch, HDFS-6482.5.patch, HDFS-6482.6.patch, HDFS-6482.7.patch,
> HDFS-6482.patch
>
>
> Right now blocks are placed into directories that are split into many
> subdirectories when capacity is reached. Instead we can use a block's ID to
> determine the path it should go in. This eliminates the need for the LDir
> data structure that facilitates the splitting of directories when they reach
> capacity as well as fields in ReplicaInfo that keep track of a replica's
> location.
> An extension of the work in HDFS-3290.
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