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From "Kai Sasaki (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (HDFS-9966) CLONE - Process block reports for erasure coded blocks
Date Tue, 15 Mar 2016 08:48:33 GMT

     [ https://issues.apache.org/jira/browse/HDFS-9966?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Kai Sasaki resolved HDFS-9966.
------------------------------
    Resolution: Invalid

> CLONE - Process block reports for erasure coded blocks
> ------------------------------------------------------
>
>                 Key: HDFS-9966
>                 URL: https://issues.apache.org/jira/browse/HDFS-9966
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>            Reporter: dragon
>            Assignee: Zhe Zhang
>             Fix For: HDFS-7285
>
>
> HDFS-7339 adds support in NameNode for persisting block groups. For memory efficiency,
erasure coded blocks under the striping layout are not stored in {{BlockManager#blocksMap}}.
Instead, entire block groups are stored in {{BlockGroupManager#blockGroups}}. When a block
report arrives from the DataNode, it should be processed under the block group that it belongs
to. The following naming protocol is used to calculate the group of a given block:
> {code}
>  * HDFS-EC introduces a hierarchical protocol to name blocks and groups:
>  * Contiguous: {reserved block IDs | flag | block ID}
>  * Striped: {reserved block IDs | flag | block group ID | index in group}
>  *
>  * Following n bits of reserved block IDs, The (n+1)th bit in an ID
>  * distinguishes contiguous (0) and striped (1) blocks. For a striped block,
>  * bits (n+2) to (64-m) represent the ID of its block group, while the last m
>  * bits represent its index of the group. The value m is determined by the
>  * maximum number of blocks in a group (MAX_BLOCKS_IN_GROUP).
> {code}



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