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Date: Tue, 20 Dec 2011 18:30:31 +0000 (UTC)
From: "stack (Commented) (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (HBASE-5074) support checksums in HBase block
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    [ https://issues.apache.org/jira/browse/HBASE-5074?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13173388#comment-13173388 ] 

stack commented on HBASE-5074:
------------------------------

Where in the read pipeline would we verify the checksum?  Down in hfile?  Where would we do the exception processing forcing reread with checksum=on?  Also down in hfile?

(Nice idea BTW)
                
> support checksums in HBase block cache
> --------------------------------------
>
>                 Key: HBASE-5074
>                 URL: https://issues.apache.org/jira/browse/HBASE-5074
>             Project: HBase
>          Issue Type: Improvement
>          Components: regionserver
>            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 into the HBase block cache 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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