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From "Konstantin Shvachko (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-4597) Under-replicated blocks are not calculated if the name-node is forced out of safe-mode.
Date Fri, 07 Nov 2008 01:40:44 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-4597?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12645659#action_12645659

Konstantin Shvachko commented on HADOOP-4597:

I'll fix Raghu's issue in subsequent issue.

> Under-replicated blocks are not calculated if the name-node is forced out of safe-mode.
> ---------------------------------------------------------------------------------------
>                 Key: HADOOP-4597
>                 URL: https://issues.apache.org/jira/browse/HADOOP-4597
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: dfs
>    Affects Versions: 0.18.0
>            Reporter: Konstantin Shvachko
>            Assignee: Konstantin Shvachko
>            Priority: Blocker
>             Fix For: 0.18.3
>         Attachments: NeededRepl-18.patch, NeededRepl.patch
> Currently during name-node startup under-replicated blocks are not added to the neededReplications
queue until the name-node leaves safe mode. This is an optimization since otherwise all blocks
will first go into the under-replicated queue and then most of them will be removed from it.
> When the name-node leaves safe-mode automatically it checks all blocks to have a correct
number of replicas ({{processMisReplicatedBlocks()}}). 
> When the name-node leaves safe-mode manually it does not perform the checkup.
> In the latter case all under-replicated blocks remain not replicated forever because
there is no alternative mechanism to trigger replications.
> The proposal is to call {{processMisReplicatedBlocks()}} any time the name-node leaves
safe mode - automatically or manually.
> In addition to solving that problem this could be an alternative mechanism for refreshing
{{neededReplications}} and {{excessReplicateMap}} sets.

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