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From Ted Yu <yuzhih...@gmail.com>
Subject Re: Too many non-used regions
Date Tue, 14 Oct 2014 10:57:55 GMT
If cluster restarts, master still needs to assign such regions. 
This would affect MTTR. 

Otherwise in a stable cluster, they shouldn't consume much resource. 

Cheers

On Oct 14, 2014, at 3:45 AM, Serega Sheypak <serega.sheypak@gmail.com> wrote:

> Ok, I got.
> And in general, region which has no R/W requests doesn't consume ny
> resources except record in META?
> 
> 2014-10-14 13:42 GMT+04:00 Ted Yu <yuzhihong@gmail.com>:
> 
>> In 0.94, load balancer doesn't take load each region receives into
>> account. It only considers the number of regions as the sole criteria for
>> balancing.
>> 
>> Thus the high number of unused regions may cause imbalance.
>> 
>> Please consider reducing unused regions.
>> 
>> Cheers
>> 
>> On Oct 14, 2014, at 2:33 AM, Serega Sheypak <serega.sheypak@gmail.com>
>> wrote:
>> 
>>> We are using CDH 4.6 (hbase-0.94.15+86)
>>> Regions are balanced.
>>> - Read/write request are pretty even,
>>> - count or regions per RegionServer is pretty even.
>>> - there are no "hot spots"
>>> 
>>> 
>>> 2014-10-14 12:50 GMT+04:00 Qiang Tian <tianq01@gmail.com>:
>>> 
>>>> region unbalanced?
>>>> which hbase release?
>>>> 
>>>> 
>>>> On Tue, Oct 14, 2014 at 3:39 PM, Serega Sheypak <
>> serega.sheypak@gmail.com>
>>>> wrote:
>>>> 
>>>>> Hi, we have 10 nodes cluster with 10HDD, 256 GB RAM and 10HDD 3TB each.
>>>>> Suddenly we met write perfomance issues.
>>>>> 
>>>>> Our workload is:
>>>>> 1. We have 100+ region table for write load. It has constant set of
>> keys
>>>>> (~6* 10^7) and we write "updates". No versions or stuff like that
>>>>> 2. We have several read-only tables, theirs size could be from 1 egion
>> up
>>>>> to 256 regions.
>>>>> 3. We have several non-used tables  theirs size could be from 1 region
>> up
>>>>> to 256 regions. These tables are previous versions of read-only tables.
>>>>> 
>>>>> Right now each RegionServer serves >100 regions, but only half of
them
>>>> are
>>>>> active. Really nothing changed for the last few weeks, we got more
>>>> non-used
>>>>> tables, but quantity on active read-only tables is the same, single
>>>>> wirte-only table dodn't get more bytes to write.
>>>>> 
>>>>> Can big count of non-used(!!!) regions affect write/read perfomance for
>>>>> tables which are in use.
>> 

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