[jira] [Commented] (HDFS-9205) Do not schedule corrupt blocks for replication

["Tsz Wo Nicholas Sze (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HDFS-9205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14947718#comment-14947718 ] 

Tsz Wo Nicholas Sze commented on HDFS-9205:
-------------------------------------------

The failure of TestReadOnlySharedStorage actually is related -- the current implementation of read-only storage breaks the corrupt block definition.  It treats blocks with read-only replicas but no normal replicas as corrupt replicas.

> Do not schedule corrupt blocks for replication
> ----------------------------------------------
>
>                 Key: HDFS-9205
>                 URL: https://issues.apache.org/jira/browse/HDFS-9205
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: namenode
>            Reporter: Tsz Wo Nicholas Sze
>            Assignee: Tsz Wo Nicholas Sze
>            Priority: Minor
>         Attachments: h9205_20151007.patch, h9205_20151007b.patch
>
>
> Corrupted blocks by definition are blocks cannot be read. As a consequence, they cannot be replicated.  In UnderReplicatedBlocks, there is a queue for QUEUE_WITH_CORRUPT_BLOCKS and chooseUnderReplicatedBlocks may choose blocks from it.  It seems that scheduling corrupted block for replication is wasting resource and potentially slow down replication for the higher priority blocks.



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