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Date: Wed, 24 Aug 2011 22:46:31 +0000 (UTC)
From: "Todd Lipcon (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
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Subject: [jira] [Commented] (HDFS-1108) Log newly allocated blocks
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    [ https://issues.apache.org/jira/browse/HDFS-1108?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13090590#comment-13090590 ] 

Todd Lipcon commented on HDFS-1108:
-----------------------------------

In the hflush case, the client calls namenode.fsync() the first time hflush() is called on a new block. This causes the blocks to get persisted, and does call logSync() already today.

> Log newly allocated blocks
> --------------------------
>
>                 Key: HDFS-1108
>                 URL: https://issues.apache.org/jira/browse/HDFS-1108
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: name-node
>            Reporter: dhruba borthakur
>            Assignee: Todd Lipcon
>             Fix For: HA branch (HDFS-1623)
>
>         Attachments: HDFS-1108.patch, hdfs-1108-habranch.txt, hdfs-1108.txt
>
>
> The current HDFS design says that newly allocated blocks for a file are not persisted in the NN transaction log when the block is allocated. Instead, a hflush() or a close() on the file persists the blocks into the transaction log. It would be nice if we can immediately persist newly allocated blocks (as soon as they are allocated) for specific files.

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