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From Ted Yu <yuzhih...@gmail.com>
Subject Re: distribution of regions to servers
Date Wed, 08 Jun 2011 19:50:16 GMT
In trunk this behavior has been improved.
Load balancer would move the youngest region off heavily loaded region

See http://zhihongyu.blogspot.com/2011/04/load-balancer-in-hbase-090.html

I am thinking of creating a new policy for region assignment at cluster
startup which assigns regions from each table in round-robin fashion.

On Wed, Jun 8, 2011 at 3:04 AM, Kleegrewe, Christian <
christian.kleegrewe@siemens.com> wrote:

> Hi geoff,
> Since hbase balances not at table but at cluster basis it may happen that
> all the regions for one table are located at the same region server. The
> reason for this may be the way hbase does table splits. If a region exceeds
> the configured maximum size the region is split into two, but both resulting
> regions are on the same region server. In the background there is a load
> balancer running that copies regions between region servers in case that the
> cluster gets unbalanced. The region that is copied does not necessarily
> belong to the table that you are actually creating. It seems to me that the
> regions copied for balancing in most cases do not belong to the table that
> is currently created but there is a simple workaround, if you want a
> balancing at table level you should disable all the other tables when
> generating a the new table.
> regards
> Christian
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> -----Original Message-----
> From: Geoff Hendrey [mailto:ghendrey@decarta.com]
> Sent: Tuesday, June 07, 2011 8:34 PM
> To: hbase-user@hadoop.apache.org
> Subject: distribution of regions to servers
> I have a table with a hundred or so regions. When I look in the hbase
> web ui, I see that all the regions are on one server. Of course we have
> many other tables and lots of data. Some tables seem to distribute their
> regions amongst many servers.
> I know there probably isn't a "pat" answer to this but: wouldn't I want
> a large table with many regions to be distributed across many machines?
> Just curious to understand the nuance. If I *do* want a uniform
> distribution of regions to servers, how would I achieve it?
> -geoff

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