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Posted to issues@hbase.apache.org by "Elliott Clark (JIRA)" <ji...@apache.org> on 2016/01/25 20:00:40 UTC

[jira] [Commented] (HBASE-7408) Make compaction to use pread instead of sequential read

    [ https://issues.apache.org/jira/browse/HBASE-7408?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15115770#comment-15115770 ] 

Elliott Clark commented on HBASE-7408:
--------------------------------------

I would guess that this was the issue with long running sequential reads blocking the short preads.

> Make compaction to use pread instead of sequential read
> -------------------------------------------------------
>
>                 Key: HBASE-7408
>                 URL: https://issues.apache.org/jira/browse/HBASE-7408
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Rishit Shroff
>            Assignee: Rishit Shroff
>            Priority: Minor
>   Original Estimate: 24h
>  Remaining Estimate: 24h
>
> As we discovered lately, HFile compactions use sequential reads to fetch blocks. It cause unwanted streaming of data from HDFS to region servers when there is a cache hit. Lets change to use preads to reduce iops on disks.



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