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https://issues.apache.org/jira/browse/HDFS-9965?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kai Sasaki resolved HDFS-9965.
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Resolution: Invalid
> CLONE - Representing striped block groups in NameNode with hierarchical
> naming protocol
> ---------------------------------------------------------------------------------------
>
> Key: HDFS-9965
> URL: https://issues.apache.org/jira/browse/HDFS-9965
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: dragon
> Assignee: Zhe Zhang
> Fix For: 3.0.0
>
>
> 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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