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From "Allen Wittenauer (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (HDFS-250) Save (sync) journal (fsimage) to alternate/secondary/read-only name node
Date Fri, 18 Jul 2014 05:09:05 GMT

     [ https://issues.apache.org/jira/browse/HDFS-250?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Allen Wittenauer resolved HDFS-250.

    Resolution: Fixed

This has been fixed a few different ways, most recently with the QJM.

> Save (sync) journal (fsimage) to alternate/secondary/read-only name node
> ------------------------------------------------------------------------
>                 Key: HDFS-250
>                 URL: https://issues.apache.org/jira/browse/HDFS-250
>             Project: Hadoop HDFS
>          Issue Type: New Feature
>            Reporter: Robert Chansler
> The name node journal records HDFS transactions. The journal can be written to multiple
file systems (but not HDFS itself!) to increase the durability of the journal. The transaction
has to wait for each copy to sync. If one of the file systems becomes slow, performance of
HDFS is affected. 
> As an alternative to directly writing a remote file, the transaction could be written
to another name node. The alternate node could be the secondary name node, or a read-only
name node replica that provides a journal service. The idea being that receipt of the record--but
not its sync to the local disk--would be good enough as a journal replica. This could provide
a fast, predictable journal replica where common-mode failures are sufficiently improbable
or tolerable.
> (1791249)

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