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From Michael Segel <michael_se...@hotmail.com>
Subject Re: HBase scan performance decreases over time.
Date Mon, 05 Nov 2012 13:04:59 GMT
There's an HDFS bandwidth setting which is set to 10MB/s. 

Way too low for even 1GBe.

Have you modified this setting yet? 


On Nov 3, 2012, at 2:50 PM, David Koch <ogdude@googlemail.com> wrote:

> Hello Ted,
> We never initiate major compaction manually. I have not looked at I/O
> balance between nodes in detail. We have noticed that after running for a
> couple of weeks HBase seems to spend hours pushing blocks between nodes in
> order to optimize things. We add data daily in one ~30gb push to several
> tables. Sometimes nodes get added to the running system.
> Where can I get more information on how to carry out performance related
> HBase administrative tasks?
> Thank you,
> /David
> On Sat, Nov 3, 2012 at 4:42 PM, Ted Yu <yuzhihong@gmail.com> wrote:
>> Can you tell us how often you run major compaction after the import ?
>> Have you noticed imbalanced read / write requests in the cluster ? Meaning
>> subset of region servers receive bulk of the writes.
>> We do some manual movement of regions when the above happens.
>> Cheers
>> On Sat, Nov 3, 2012 at 8:12 AM, David Koch <ogdude@googlemail.com> wrote:
>>> Hello,
>>> Every now and then we need to flatten our cluster and re-import all data
>>> from log files (changes in data format, etc.) Afterwards we notice a
>>> significant increase in scan performance. As data is added and shuffled
>>> around between region servers, performance goes down again over time
>> (say a
>>> couple of weeks). Are there any routine operations that one should run
>>> manually, or settings to activate in the HBase configuration to keep the
>>> data well distributed? We use HBase 0.92 as part of a Cloudera4 cluster.
>>> Thank you,
>>> /David

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