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From "Robert Chansler (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-2330) Preallocate transaction log to improve namenode transaction logging performance
Date Wed, 27 Aug 2008 00:04:44 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-2330?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12625912#action_12625912
] 

Robert Chansler commented on HADOOP-2330:
-----------------------------------------

Still PA?

> Preallocate transaction log to improve namenode transaction logging performance
> -------------------------------------------------------------------------------
>
>                 Key: HADOOP-2330
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2330
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: dfs
>    Affects Versions: 0.17.2
>            Reporter: dhruba borthakur
>            Assignee: dhruba borthakur
>             Fix For: 0.19.0
>
>         Attachments: preallocateTransactionLog.patch, preallocateTransactionLog.patch,
preallocateTransactionLog2.patch, preallocateTransactionLog3.patch, preallocateTransactionLog4.patch
>
>
> In the current implementation, the transaction log is opened in "append" mode and every
new transaction is written to the end of the log. This means that new blocks get allocated
to the edits file frequently.
> It is worth measuring the performance improvement when big chunks of the transaction
log are allocated up front. Adding new transactions do not cause frequent block allocations
for the edits log.

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