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From: William Kang <weliam.cloud@gmail.com>
Date: Wed, 6 Oct 2010 17:36:45 -0400
Message-ID: <AANLkTim1UJKp3b9SoNX5L89hLKv3FyMRASSTsbFHgqqK@mail.gmail.com>
Subject: Re: Can I pick which region server to store my row?
To: user@hbase.apache.org
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By the way, where can I get a stable version of 0.90? Thanks.


Cao

On Wed, Oct 6, 2010 at 12:54 PM, Jean-Daniel Cryans <jdcryans@apache.org>wrote:

> Like Stack said, it's available in 0.90 which we're currently wrapping
> up (so not in 0.20.x).
>
> Distributing regions and distributing blocks is orthogonal (ish, but
> for this discussion let's not mix the two together), the former being
> assumed by the HBase master and the latter being assumed by the
> Namenode. Maybe this blog post can help you understanding how HBase
> uses HDFS
> http://www.larsgeorge.com/2009/10/hbase-architecture-101-storage.html
>
> J-D
>
> On Tue, Oct 5, 2010 at 8:38 PM, William Kang <weliam.cloud@gmail.com>
> wrote:
> > So, I can use the 'move' command to manually balance the load? Is this
> > available to 0.20.6? Was there any automatic balance mechanism in hbase
> > before if the replicated block is not for load distribution purpose?
> Thanks.
> >
> >
> > William
> >
> > On Tue, Oct 5, 2010 at 11:19 PM, Stack <stack@duboce.net> wrote:
> >
> >> In 0.90, you can turn off the balancer and then distribute the regions
> >> any way you wish with new 'move' command.
> >> St.Ack
> >>
> >> On Tue, Oct 5, 2010 at 8:13 PM, Jean-Daniel Cryans <jdcryans@apache.org
> >
> >> wrote:
> >> > A row is always served a single region, so the question is more about
> >> > region distribution. In 0.20 and 0.89 you have no control over that
> >> > (the best you can do is calling close_region in the shell, where is
> >> > the region will be moved is "random"), but things are getting better
> >> > in 0.90 where you'll be able to move regions manually.
> >> >
> >> > HBase doesn't create multiple copies of HFiles to distribute load,
> >> > what happens is each block is replicated 3 times by HDFS and this is
> >> > invisible to HBase. This is done for data safety rather than
> >> > distributing the load.
> >> >
> >> > J-D
> >> >
> >> > On Tue, Oct 5, 2010 at 8:05 PM, William Kang <weliam.cloud@gmail.com>
> >> wrote:
> >> >> Hi folks,
> >> >> I have a general question about Hbase. Can we pick which region
> server
> >> we
> >> >> want to save a particular row? The reason I am asking this is because
> >> >> sometimes we want to manually balance region servers' load. If we
> could
> >> >> assign particular rows to particular region servers, we can have that
> >> >> control. I understand that Hbase will balance its load automatically
> by
> >> >> create multiple copies of hfiles in HDFS. But, we do want to have
> more
> >> >> control over that. Is it possible or is it already in Hbase but we
> >> didn't
> >> >> find it? Many thanks.
> >> >>
> >> >>
> >> >> William
> >> >>
> >> >
> >>
> >
>

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