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Date: Mon, 20 Jun 2011 05:31:48 +0000 (UTC)
From: "Todd Lipcon (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
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Subject: [jira] [Commented] (HDFS-2080) Speed up DFS read path
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    [ https://issues.apache.org/jira/browse/HDFS-2080?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13051807#comment-13051807 ] 

Todd Lipcon commented on HDFS-2080:
-----------------------------------

One bug I'm aware is probably in this is that the append code path doesn't currently deal with the case where the writer wants to use a different checksum type compared to the original block file. We probably need to change the append response to have the server tell the client which checksum to use.

> Speed up DFS read path
> ----------------------
>
>                 Key: HDFS-2080
>                 URL: https://issues.apache.org/jira/browse/HDFS-2080
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: hdfs client
>    Affects Versions: 0.23.0
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>             Fix For: 0.23.0
>
>         Attachments: hdfs-2080.txt
>
>
> I've developed a series of patches that speeds up the HDFS read path by a factor of about 2.5x (~300M/sec to ~800M/sec for localhost reading from buffer cache) and also will make it easier to allow for advanced users (eg hbase) to skip a buffer copy. 

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