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From Chris Curtin <curtin.ch...@gmail.com>
Subject Re: Number of Under-Replicated Blocks ?
Date Tue, 21 Feb 2012 14:57:33 GMT
Have you had any Name Node failures lately? I had them every couple of days
and found that there were files being left in hdfs
/log/hadoop/tmp/mapred/staging/... when communications with the Name Node
was lost. Not sure why they never got replicated correctly (maybe because
they are in /log?)

I went in and removed the old files (say 2 days older or older) and saw the
# of blocks drop to 0.

Hope this helps,

Chris

On Mon, Feb 20, 2012 at 1:25 AM, praveenesh kumar <praveenesh@gmail.com>wrote:

> I recently added a new DN/TT to my cluster. Could it be the reason for such
> behaviour ?
>
> Thanks,
> Praveenesh
>
> On Mon, Feb 20, 2012 at 11:51 AM, Harsh J <harsh@cloudera.com> wrote:
>
> > Hi,
> >
> > The tool "hadoop fsck" will tell you which files are under replicated
> > with a count of what was expected instead, just run it over /.
> >
> > While it isn't a 'normal' thing to see it come up suddenly it is still
> > in the safe zone, and is most likely an indicator that either one of
> > your DN or one of its disks has gone bad, or you have a bad
> > mapred.submit.replication value for your cluster size (default is 10
> > replicas for all MR job submit data), or bit rot of existing blocks on
> > HDDs around the cluster, etc. -- You can mostly spot the pattern of
> > files causing it by running the fsck and obtaining the listing.
> >
> > On Mon, Feb 20, 2012 at 11:43 AM, praveenesh kumar <praveenesh@gmail.com
> >
> > wrote:
> > > Hi,
> > >
> > > I am suddenly seeing some under-replicated blocks on my cluster.
> Although
> > > its not causing any problems, but It seems like few blocks are not
> > > replicated properly.
> > >
> > > Number of Under-Replicated Blocks     :     147
> > >
> > > Is it okay behavior on hadoop. If no, How can I know what are the files
> > > with under-replicated blocks and how can I configure it properly to
> > reduce
> > > the number of under-replicated blocks.
> > >
> > > Thanks,
> > > Praveenesh
> >
> >
> >
> > --
> > Harsh J
> > Customer Ops. Engineer
> > Cloudera | http://tiny.cloudera.com/about
> >
>

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