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From Suresh Srinivas <sures...@yahoo-inc.com>
Subject Re: decommission a rack
Date Thu, 06 Jan 2011 20:59:22 GMT
Removing from slaves file only prevents launching datanode process on that node.

If you you use dfs.hosts configuration to set include file with list of datanodes, remove
it from that as well. This will ensure:

 *   datanode cannot register with the namenode.
 *   datanode will not be shown in the dead list.

Regards,
Suresh


On 1/6/11 12:53 PM, "Michael Segel" <michael_segel@hotmail.com> wrote:




Its ok if its in the dead column.
Take it out of your slaves file and when you reboot, it will not show up at all.
Until then its just a foot note in history. :-)

> Date: Wed, 5 Jan 2011 21:24:57 -0500
> Subject: Re: decommission a rack
> From: magawake@gmail.com
> To: general@hadoop.apache.org
>
> Thanks for the response.
>
> I did decommission the server and it took couple of minutes. However,
> I see the server in my "Dead Datanotes" page. How can I completely
> forget about this box?
>
>
> On Wed, Jan 5, 2011 at 10:01 AM, Segel, Mike <msegel@navteq.com> wrote:
> > Change your topology script?
> >
> > One thing about rack awareness. You never want to have an unbalanced configuration.
The caveat is if your uplinks between the ToR Switch  are 'fat' enough. (4 10GBe should do
it.)
> >
> > If you watched your system with the one machine on a separate rack (assuming it
was also on a separate switch) you'd see a major network bottle neck. (We use Ganglia)
> >
> > If you're seeing the rack count wrong, you could just bounce the cloud and it should
show only two.
> >
> > Note: Deprecating a machine can take a long time. You may want to consider just
killing the node, waiting till the cluster recognizes that its down and I believe just kicking
off an FSCK or maybe running the balancer program will clean that up faster than deprecating.
(YMMV)
> >
> > HTH
> >
> > -Mike
> >
> >
> > -----Original Message-----
> > From: Mag Gam [mailto:magawake@gmail.com]
> > Sent: Wednesday, January 05, 2011 5:56 AM
> > To: general@hadoop.apache.org
> > Subject: decommission a rack
> >
> > Using 0.21
> >
> > I have a server which was in rack3. It was the only server in this
> > rack so I decommissioned the server. fsck shows only 2 racks however
> > topology shows 3 racks. How can I fix this?
> >
> >
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