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From Jean-Daniel Cryans <jdcry...@apache.org>
Subject Re: Can I pick which region server to store my row?
Date Thu, 07 Oct 2010 02:51:48 GMT
0.90.0 wasn't released yet, the current stable version is 0.20.6

For more information on HBase versions, see
http://wiki.apache.org/hadoop/Hbase/HBaseVersions

J-D

On Wed, Oct 6, 2010 at 2:36 PM, William Kang <weliam.cloud@gmail.com> wrote:
> 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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