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From 吴限 <infinity0...@gmail.com>
Subject Re: data loss due to regionserver going down
Date Wed, 27 Jul 2011 16:33:23 GMT
Dear Stack, thx for your reply~
First I don't know if there is something wrong with the cdh3u0.
And thx for ur reminding me about the replication property,which I didn't
quite understand but now understands. I'll try to correct this mistake.
But actually these situations which I have described really happens with
the replication being set to 1. And that's why I find these quite weird .
I just started trying hbase a month ago and there exist a lot of things i
don't quite understand.
Hope to get replied. Thanks~
2011/7/28 Stack <stack@duboce.net>

> On Wed, Jul 27, 2011 at 8:58 AM, 吴限 <infinity0222@gmail.com> wrote:
> > Setup:
> >   -cdh3u0
> >   - Hadoop 0.20.2
>
> You are using the hadoop from cdh3u0?
>
>
> >   - dfs.replication is set to 1
> >
>
> You will lose data if a machine goes away. You have two machines but
> only one instance of each data block; think of it as half of your data
> one one node and the rest on another.  If you kill one machine, half
> your data is gone.
>
>
> >  After I restarted the regionserver which I had rebooted and checked
> again,
> >  I found that some of the missing data was got back but there still
> existed
> > some data which hadn't been found yet.
>
>
> I wonder what was going on here that we didn't see it all restored.
>
>
> >  This is problematic since we are supposed to
> > replicate at x1, so at least one other node should be able to
> > theoretically serve the *data* that the downed regionserver can't.
> >
>
> No.  The behavior you describe would come with replication of 2, not 1.
>
> St.Ack
>

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