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https://issues.apache.org/jira/browse/ACCUMULO-2866?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14020107#comment-14020107
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Eric Newton commented on ACCUMULO-2866:
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In the normal case, WALs are written out and never re-read. But, if a tablet
is lost, the contents of memory have to be recovered. The master coordinates
getting the WAL sorted into a recovery file. The tservers use the sorted
recovery file to re-load the data that was in memory, and not yet flushed to
disk.
WAL file = not sorted, rarely read
recovery file = sorted, and read by all recovering tablets/servers.
> 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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