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From "Suresh Srinivas (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-2699) Store data and checksums together in block file
Date Tue, 20 Dec 2011 00:51:30 GMT

    [ https://issues.apache.org/jira/browse/HDFS-2699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13172800#comment-13172800
] 

Suresh Srinivas commented on HDFS-2699:
---------------------------------------

Dhruba, say CRC inlining is done and reduces number of IOPs by half. Does it solve the number
of IOPs bottleneck for HBase or does it just provide a relief?
                
> 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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