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From Brennon Church <bren...@getjar.com>
Subject Re: HBase table affinity to host(s)
Date Sun, 23 Dec 2012 22:59:32 GMT
I'm curious.  If I disable the hbase balancer, what happens when a 
regionserver goes offline?  Will those regions get moved over to the 
remaining hosts as would normally be the case?  Or will they remain 
unavailable until the balancer is run manually?



On 12/22/12 5:48 AM, Ted Yu wrote:
> When region splits, the daughter regions would be placed on the same server
> as parent region.
> You also need to consider the case where new server crashes and its regions
> are moved to older system.
> In HBASE-5231 <https://issues.apache.org/jira/browse/HBASE-5231> you can
> find a patch which does per table load balancing. You can modify that code
> to move regions of selected table to pre-defined group of servers
> (specified through configuration).
> Cheers
> On Fri, Dec 21, 2012 at 11:01 PM, Brennon Church <brennon@getjar.com> wrote:
>> I do allow regions from other tables on the newer servers.  The issue
>> stems from a single table that habitually causes hot regions. Not such a
>> problem on the new servers, but when those regions hit the older systems
>> bad things happen.  I think the proper long-term solution is to change the
>> code writing to the table, but that's not something that can be done right
>> now, so I'm looking for the second best option.
>> The HBASE-6721 option sounds perfect, if I'm reading it correctly. It
>> doesn't quite fit my use case, but would solve the problem regardless.
>> If I understand the balancer part correctly, a possible but ugly (IMHO)
>> option would be to move the region(s) causing trouble over to the more
>> powerful servers then disable automatic balancing.  Would region splits
>> then remain on the same system as the original region?  If so, it would
>> work around the problem but at the expense of having to manually move
>> regions around more frequently to keep everything else balanced.
>> Thanks.
>> --Brennon
>> On 12/21/12 8:48 PM, Ted Yu wrote:
>>> Brennon:
>>> I forgot to ask you about other tables you have. Do you allow regions of
>>> other tables to also be assigned to this group of newer servers ?
>>> If you do, there is possibility that the combined load on such new servers
>>> would make response from them slow.
>>> Cheers
>>> On Fri, Dec 21, 2012 at 8:28 PM, Ted Yu <yuzhihong@gmail.com> wrote:
>>>   What you describe is akin to HBASE-6721 region server group.
>>>> Basically you want this table to be bound to group of region servers.
>>>> Development for 0.94 is on-going, to my knowledge.
>>>> Cheers
>>>> On Fri, Dec 21, 2012 at 7:30 PM, Brennon Church <brennon@getjar.com
>>>>> wrote:
>>>>   0.92.0
>>>>> I was looking at the balancer option.  I'm loathe to turn the automatic
>>>>> balancer off and handle it manually as we have a lot of regions.  Is
>>>>> that
>>>>> the option you were thinking of?  Or am I missing something?
>>>>> Thanks.
>>>>> --Brennon
>>>>> On 12/21/12 4:19 PM, Ted Yu wrote:
>>>>>   Currently there is no such capability - you may need to customize load
>>>>>> balancer.
>>>>>> What version of HBase are you using ?
>>>>>> Cheers
>>>>>> On Fri, Dec 21, 2012 at 3:54 PM, Brennon Church <brennon@getjar.com>
>>>>>> wrote:
>>>>>>    I'm curious, is there any concept of hosting regions from a given
>>>>>> table
>>>>>>> only on a single host or subset of hosts in a cluster?  In our
case we
>>>>>>> have
>>>>>>> a heavily-used table that can cause problems for the older systems
>>>>>>> our
>>>>>>> cluster.  Newer systems would have less trouble, so I'd like
>>>>>>> restrict
>>>>>>> regions for that one table only to those more powerful servers.
>>>>>>> Thanks.
>>>>>>> --Brennon

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