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https://issues.apache.org/jira/browse/ACCUMULO-2842?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14033921#comment-14033921
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Josh Elser commented on ACCUMULO-2842:
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Orthogonal for the most part. I believe this will only save you when you're
closing the file (e.g. a WAL), not the incremental syncs that we expect to
happen after we have updated entries in the metadata table, for example. If you
have some power outage without using {{hsync}} before we close a file (which,
remember, happens when we hit that max WAL size), I do not believe
{{dfs.datanode.synconclose}} does anything for you.
I think you could say this would be a middle ground between {{hflush}}
everything, {{hflush}} normally but {{(h)sync}} on close, and {{hsync}}
everything, but I would want to re-read some datanode code before you quote
that :)
> Allow for use of hflush instead of hsync
> ----------------------------------------
>
> Key: ACCUMULO-2842
> URL: https://issues.apache.org/jira/browse/ACCUMULO-2842
> Project: Accumulo
> Issue Type: Improvement
> Components: logger
> Reporter: Josh Elser
> Assignee: Josh Elser
> Fix For: 1.5.2, 1.6.1, 1.7.0
>
>
> We keep getting onto the discussion on hsync versus hflush performance;
> however, we lack a way to actually test this.
> Make the invocation of hflush or hsync configurable. It should not change the
> default, so users on existing major releases should not be affected unless
> they choose to change their configuration.
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