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From "Phabricator (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-5074) support checksums in HBase block cache
Date Mon, 27 Feb 2012 22:01:59 GMT

    [ https://issues.apache.org/jira/browse/HBASE-5074?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13217619#comment-13217619
] 

Phabricator commented on HBASE-5074:
------------------------------------

todd has commented on the revision "[jira] [HBASE-5074] Support checksums in HBase block cache".

INLINE COMMENTS
  src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:257 maybe we can add a static
final int majorVersion = 2; in this class, so the version checks are there, but it doesn't
take up heap space? Then when/if we add a v3, we can make it non-final non-static without
having to hunt down all the places where we might have major-version assumptions? The JIT
will happily optimize out any if-statements against the constant.

REVISION DETAIL
  https://reviews.facebook.net/D1521

                
> 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
>         Attachments: D1521.1.patch, D1521.1.patch, D1521.10.patch, D1521.10.patch, D1521.10.patch,
D1521.10.patch, D1521.10.patch, D1521.2.patch, D1521.2.patch, D1521.3.patch, D1521.3.patch,
D1521.4.patch, D1521.4.patch, D1521.5.patch, D1521.5.patch, D1521.6.patch, D1521.6.patch,
D1521.7.patch, D1521.7.patch, D1521.8.patch, D1521.8.patch, D1521.9.patch, D1521.9.patch
>
>
> 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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