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From "Hudson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-7339) Representing striped block groups in NameNode with hierarchical naming protocol
Date Wed, 30 Sep 2015 19:38:15 GMT

    [ https://issues.apache.org/jira/browse/HDFS-7339?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14938554#comment-14938554
] 

Hudson commented on HDFS-7339:
------------------------------

FAILURE: Integrated in Hadoop-Mapreduce-trunk-Java8 #465 (See [https://builds.apache.org/job/Hadoop-Mapreduce-trunk-Java8/465/])
HDFS-7339. Allocating and persisting block groups in NameNode. (zhezhang: rev bc2833b1c91e107d090619d755c584f6eae82327)
* hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/SequentialBlockIdGenerator.java
* hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
* hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
* hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INodeFile.java
* hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/SequentialBlockGroupIdGenerator.java
* hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockIdManager.java
* hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddBlockgroup.java


> Representing striped block groups in NameNode with hierarchical naming protocol
> -------------------------------------------------------------------------------
>
>                 Key: HDFS-7339
>                 URL: https://issues.apache.org/jira/browse/HDFS-7339
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>            Reporter: Zhe Zhang
>            Assignee: Zhe Zhang
>         Attachments: HDFS-7339-001.patch, HDFS-7339-002.patch, HDFS-7339-003.patch, HDFS-7339-004.patch,
HDFS-7339-005.patch, HDFS-7339-006.patch, HDFS-7339-007.patch, HDFS-7339-008.patch, Meta-striping.jpg,
NN-stripping.jpg
>
>
> All erasure codec operations center around the concept of _block group_; they are formed
in initial encoding and looked up in recoveries and conversions. A lightweight class {{BlockGroup}}
is created to record the original and parity blocks in a coding group, as well as a pointer
to the codec schema (pluggable codec schemas will be supported in HDFS-7337). With the striping
layout, the HDFS client needs to operate on all blocks in a {{BlockGroup}} concurrently. Therefore
we propose to extend a file’s inode to switch between _contiguous_ and _striping_ modes,
with the current mode recorded in a binary flag. An array of BlockGroups (or BlockGroup IDs)
is added, which remains empty for “traditional” HDFS files with contiguous block layout.
> The NameNode creates and maintains {{BlockGroup}} instances through the new {{ECManager}}
component; the attached figure has an illustration of the architecture. As a simple example,
when a {_Striping+EC_} file is created and written to, it will serve requests from the client
to allocate new {{BlockGroups}} and store them under the {{INodeFile}}. In the current phase,
{{BlockGroups}} are allocated both in initial online encoding and in the conversion from replication
to EC. {{ECManager}} also facilitates the lookup of {{BlockGroup}} information for block recovery
work.



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