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Posted to hdfs-dev@hadoop.apache.org by "Varun Sharma (JIRA)" <ji...@apache.org> on 2013/07/07 18:35:49 UTC

[jira] [Created] (HDFS-4960) Unnecessary .meta seeks even when skip checksum is true

Varun Sharma created HDFS-4960:
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             Summary: Unnecessary .meta seeks even when skip checksum is true
                 Key: HDFS-4960
                 URL: https://issues.apache.org/jira/browse/HDFS-4960
             Project: Hadoop HDFS
          Issue Type: Improvement
    Affects Versions: 3.0.0, 2.1.0-beta
            Reporter: Varun Sharma


While attempting to benchmark an HBase + Hadoop 2.0 setup on SSDs, we found unnecessary seeks into .meta files, each seek was a 7 byte read at the head of the file - this attempts to validate the version #. Since the client is requesting no-checksum, we should not be needing to touch the .meta file at all.

Since the purpose of skip checksum is to also avoid the performance penalty of the extra seek, we should not be seeking into .meta if skip checksum is true

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