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From "Jim Kellerman (POWERSET)" <Jim.Keller...@microsoft.com>
Subject RE: State of HA
Date Fri, 19 Jun 2009 18:51:30 GMT
Andrew,

For questions about the name node, you should ask on hadoop-user@hadoop.apache.org


> -----Original Message-----
> From: Andrew Wharton [mailto:andrew.wharton@nokia.com]
> Sent: Friday, June 19, 2009 11:40 AM
> To: hbase-user@hadoop.apache.org
> Subject: Re: State of HA
>
> Does anybody know the state of the Backupnamenode scheme that is
> referenced here? I am looking for a Jira ticket that might give me some
> more insight into the timeline for release. The hadoop-general email
> list doesn't seem to have any information about this issue, which is
> kind of worrying...
>
> TIA.
>
> -- Andrew
>
> On Tue, 2009-06-02 at 16:57 +0200, ext Jean-Daniel Cryans wrote:
> > Andrew,
> >
> > I think you are confusing some components of the whole stack here. The
> > Namenode is the master for HDFS just like the HMaster is the master
> > for HBase. Hadoop is 2 things : HDFS and an implementation of
> > MapReduce which also has a master, the JobTracker. HBase sits on all
> > that.
> >
> > So with regards with what's fixed, the HMaster SPOF is fixed for 0.20.
> > The Namenode in 0.20 is still a SPOF. That means, if you want HA, you
> > should get a really reliable machine for the Namenode but you can put
> > the HMaster on any nodes you want.
> > AFAIK, there is a BackupNamenode in Hadoop 0.21 that serves as a
> > Namenode failover.
>
>


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