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From rahul patodi <patodira...@gmail.com>
Subject Re: namenode doesn't start after reboot
Date Thu, 23 Dec 2010 15:29:19 GMT
Hi,
If you want to reboot the server:
1. stop mapred
2. stop dfs
the reboot
when you again want to restart hadoop
firstly start dfs then mepred.

-- 
*Regards*,
Rahul Patodi
Software Engineer,
Impetus Infotech (India) Pvt Ltd,
www.impetus.com
Mob:09907074413


On Thu, Dec 23, 2010 at 6:15 PM, li ping <li.j2ee@gmail.com> wrote:

> As far as I know, setup a backup namenode dir is enough.
>
> I haven't use the hadoop in a production environment. So, I can't tell you
> what would be right way to reboot the server.
>
> On Thu, Dec 23, 2010 at 6:50 PM, Bjoern Schiessle <bjoern@schiessle.org
> >wrote:
>
> > Hi,
> >
> > On Thu, 23 Dec 2010 09:30:17 +0800 li ping wrote:
> > > It seems the exception occurs during NameNode loads the editlog.
> > > make sure the editlog file exists. or you can debug the application to
> > > see what's wrong.
> >
> > last night I tried to fix the problem and did a big mistake. Instead of
> > copying /var/lib/hadoop-0.20/cache/hadoop/dfs/name/current/edits and
> > edits.new to a backup I moved them and later delete the only version
> > hence I thought I have a copy.
> >
> > The good thing: The namenode starts again.
> > The bad thing: My file system is now in an inconsistent state.
> >
> > Probably the only solution is to reformat the hdfs and start from
> > scratch. Thankfully there wasn't that much data stored at the hdfs until
> > now but I definitely have to make sure that this doesn't happens again:
> >
> > 1. I have set up a second dfs.name.dir which is stored at another
> > computer (mounted by sshfs)
> > 2. I will install a backup script similar to:
> > http://blog.milford.io/2010/10/simple-hadoop-namenode-backup-script
> >
> > Do you think this should be enough to overcome such situations in the
> > future? Any additional ideas how to make it more safe?
> >
> > I'm still a little bit afraid if I think about the next time I will have
> > to reboot the server. Shouldn't a reboot safely stop and restart all
> > Hadoop services? Is there any thing I can do to make sure that the next
> > reboot will not cause the same problems?
> >
> > Thanks a lot!
> > Björn
> >
> >
> >
>
>
> --
> -----李平
>

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