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From "Boris Shkolnik (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HDFS-1172) Blocks in newly completed files are considered under-replicated too quickly
Date Sat, 19 Mar 2011 00:59:29 GMT

    [ https://issues.apache.org/jira/browse/HDFS-1172?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13008703#comment-13008703
] 

Boris Shkolnik commented on HDFS-1172:
--------------------------------------

I agree that 5 minutes is too long, but putting it into pendingReplication still seems to
be more appropriate. May be we can modify pendingReplication monitor to adjust check interval
dynamically to the next 'timing out' replication. This would, of course, require having timeOut
value per replication (or we can reuse timeStamp for that).

> Blocks in newly completed files are considered under-replicated too quickly
> ---------------------------------------------------------------------------
>
>                 Key: HDFS-1172
>                 URL: https://issues.apache.org/jira/browse/HDFS-1172
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: name-node
>    Affects Versions: 0.21.0
>            Reporter: Todd Lipcon
>         Attachments: HDFS-1172.patch
>
>
> I've seen this for a long time, and imagine it's a known issue, but couldn't find an
existing JIRA. It often happens that we see the NN schedule replication on the last block
of files very quickly after they're completed, before the other DNs in the pipeline have a
chance to report the new block. This results in a lot of extra replication work on the cluster,
as we replicate the block and then end up with multiple excess replicas which are very quickly
deleted.

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