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From "Luke Lu (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-2699) Store data and checksums together in block file
Date Sat, 17 Dec 2011 12:42:30 GMT

    [ https://issues.apache.org/jira/browse/HDFS-2699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13171539#comment-13171539
] 

Luke Lu commented on HDFS-2699:
-------------------------------

bq. You'd need HFile v3 for this

Or come up new compression codecs for compression codecs (including none) that don't have
checksums.
                
> Store data and checksums together in block file
> -----------------------------------------------
>
>                 Key: HDFS-2699
>                 URL: https://issues.apache.org/jira/browse/HDFS-2699
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>            Reporter: dhruba borthakur
>            Assignee: dhruba borthakur
>
> The current implementation of HDFS stores the data in one block file and the metadata(checksum)
in another block file. This means that every read from HDFS actually consumes two disk iops,
one to the datafile and one to the checksum file. This is a major problem for scaling HBase,
because HBase is usually  bottlenecked on the number of random disk iops that the storage-hardware
offers.

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