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https://issues.apache.org/jira/browse/HBASE-17083?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15665880#comment-15665880
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Ashu Pachauri commented on HBASE-17083:
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One thing that we noticed in production workload is that hedged reads are very
good at eliminating outlier datanodes, which in turn makes them very good
choice for latency sensitive setups. But, if you are looking for maximizing
throughput, hedged reads tend to create load amplification as thing get slower
in general. In short, the thing to watch out for is the non graceful
performance degradation when you are running close a certain throughput
threshold.
> Enable hedged reads by default in hbase-2.0.0
> ---------------------------------------------
>
> Key: HBASE-17083
> URL: https://issues.apache.org/jira/browse/HBASE-17083
> Project: HBase
> Issue Type: Improvement
> Affects Versions: 2.0.0
> Reporter: stack
> Assignee: stack
> Priority: Critical
> Fix For: 2.0.0
>
>
> Hedged reads came in in hadoop-2.4. hbase-2.0.0 requires a later version so
> we can expect support to be preseent. This issue is about a bit of testing to
> show defined benefit when hedged reads are on and then enabling them by
> default in hbase-2.0.0.
> See http://hbase.apache.org/book.html#_hedged_reads for current state of the
> doc.
> This issue came up in conversation a few of us were having Thursday and then
> Lars George started asking me their state in the last 24 hours.
> Assigning myself to do the bit of testing and enabling.
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