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Posted to notifications@accumulo.apache.org by "Josh Elser (JIRA)" <ji...@apache.org> on 2014/06/06 19:06:03 UTC

[jira] [Commented] (ACCUMULO-2866) Default WAL size should be based on HDFS Block Size

    [ https://issues.apache.org/jira/browse/ACCUMULO-2866?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14020055#comment-14020055 ] 

Josh Elser commented on ACCUMULO-2866:
--------------------------------------

One nice thing about setting a very large block size on the WALs (which is really like 1.05% of the configured value) is that when insufficient DFS space exists, we fail quickly. Granted, it fails in a really obscure way (looks more like a permission error iirc), but it still fails immediately instead of some time later.

I'd be curious in some basic before/after numbers too. I am not knowledgeable enough off the top of my head if something in the DFS pipeline would be suffering by us doing this. 

> Default WAL size should be based on HDFS Block Size
> ---------------------------------------------------
>
>                 Key: ACCUMULO-2866
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-2866
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: tserver
>            Reporter: Mike Drob
>            Priority: Minor
>              Labels: wal
>             Fix For: 1.7.0
>
>
> HBase automatically defaults their WAL size to 0.95 * HDFS block size. This makes a lot of sense from a resource management perspective, and we should do the same.



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