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Date: Fri, 12 Apr 2013 13:17:23 -0400
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 <CAGpTDNfmSfHFmj9ZovcVXQs5rOL7m8EGh=re24X9=UbO7K2mog@mail.gmail.com>
Subject: Re: hbase-0.94.6.1 balancer issue
From: Jean-Daniel Cryans <jdcryans@apache.org>
To: "user@hbase.apache.org" <user@hbase.apache.org>
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Samir,

When you say "And at what point balancer will start redistribute regions to
second server", do you mean that when you look at the master's web UI you
see that one region server has 0 region? That would be a problem. Else,
that line you posted in your original message should be repeated for each
table, and globally the regions should all be correctly distributed...
unless there's an edge case where when you have only tables with 1 region
it puts them all on the same server :)

Thx,

J-D


On Fri, Apr 12, 2013 at 12:37 PM, Samir Ahmic <ahmic.samir@gmail.com> wrote:

> Thanks for explaining Jean-Marc,
>
> We are using 0.90.4 for very long time and balancing was based on total
> number of regions.That is why i was surprised with balancer log on 0.94.
> Well i'm more ops guy then dev i handle what other develop :)
>
> Regards
>
>
> On Fri, Apr 12, 2013 at 6:24 PM, Jean-Marc Spaggiari <
> jean-marc@spaggiari.org> wrote:
>
> > Hi Samir,
> >
> > Since regions are balanced per table, as soon as you will have more than
> > one region in your table, balancer will start to balance the regions over
> > the servers.
> >
> > You can split some of those tables and will you start to see HBase
> balance
> > them. This is normal behavior for 0.94. I don't know for versions before
> > that.
> >
> > Also, are you sure you need 48 tables? And not less tables with more CFs?
> >
> > JM
> >
> > 2013/4/12 Samir Ahmic <ahmic.samir@gmail.com>
> >
> > > Hi, JM
> > >
> > > I have 48 tables and as you said it is 1 region per table since i did
> not
> > > reach splitting limit yet. So this is normal behavior  in 0.94.6.1
> > version
> > > ?  And at what point balancer will start redistribute regions to second
> > > server ?
> > >
> > > Thanks
> > > Samir
> > >
> > >
> > > On Fri, Apr 12, 2013 at 6:06 PM, Jean-Marc Spaggiari <
> > > jean-marc@spaggiari.org> wrote:
> > >
> > > > Hi Samir,
> > > >
> > > > Regions are balancer per table.
> > > >
> > > > So if you have 48 regions within the same table, it should be split
> > about
> > > > 24 on each server.
> > > >
> > > > But if you have 48 tables with 1 region each, the for each table, the
> > > > balancer will see only 1 region and will display the message you saw.
> > > >
> > > > Have you looked at the UI? What do you have in it? Can you please
> > confirm
> > > > if yo uhave 48 tables or 1 table?
> > > >
> > > > Thanks,
> > > >
> > > > JM
> > > >
> > > >
> > > > 2013/4/12 Samir Ahmic <ahmic.samir@gmail.com>
> > > >
> > > > > Hi, all
> > > > >
> > > > > I'm evaluating hbase-0.94.6.1 and i have 48 regions on 2 node
> > cluster.
> > > I
> > > > > was restarting on of RSs and after that tried to balance cluster by
> > > > running
> > > > > balancer from shell. After running command regions were not
> > distributed
> > > > to
> > > > > second RS and i found this line i master log:
> > > > >
> > > > > 2013-04-12 16:45:15,589 INFO
> > > org.apache.hadoop.hbase.master.LoadBalancer:
> > > > > Skipping load balancing because balanced cluster; servers=2
> > *regions=1
> > > > > *average=0.5
> > > > > mostloaded=1 leastloaded=0
> > > > >
> > > > > This look like to me that wrong number of regions is reported by
> > > balancer
> > > > > and that cause of  skipping load balancing . In hbase shell i see
> all
> > > 48
> > > > > tables that i have and everything else looks fine.
> > > > >
> > > > > Did someone else see this type of behavior ? Did something changed
> > > around
> > > > > balancer in hbase-0.94.6.1 ?
> > > > >
> > > > > Regards
> > > > > Samir
> > > > >
> > > >
> > >
> >
>

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