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From Jean-Marc Spaggiari <jean-m...@spaggiari.org>
Subject Re: Short-circuit reads
Date Mon, 28 Jan 2013 12:45:29 GMT
Thanks J-D.

I found it with JConsole in hadoop/HBase/RegionServerStatistics/Attributes.

JM

2013/1/27, Jean-Daniel Cryans <jdcryans@apache.org>:
> It's in the region server metrics and also published through JMX.
>
> J-D
>
> On Sun, Jan 27, 2013 at 2:55 PM, Jean-Marc Spaggiari
> <jean-marc@spaggiari.org> wrote:
>> Hi J-D,
>>
>> In your presentation, where are you getting the
>> hdfsBlocksLocalityIndex value? I'm not able to find it in my UI...
>>
>> Thanks,
>>
>> JM
>>
>> 2013/1/27, Jean-Daniel Cryans <jdcryans@apache.org>:
>>> On Sun, Jan 27, 2013 at 2:38 PM, Jean-Marc Spaggiari
>>> <jean-marc@spaggiari.org> wrote:
>>>> Does this have a significant increase on HBase performances?
>>>
>>> Ted beats me to linking to my own presentation :P
>>>
>>>> And what
>>>> are the "risks" associated with short-circuit activation (if any)? No
>>>> risks of corrupting data?
>>>
>>> No, nothing, apart.
>>>
>>>>
>>>> Can this be activated after tables are already populated?
>>>
>>> Not related at all, this is a region server configuration.
>>>
>>>>
>>>> JM
>>>>
>>>> 2013/1/27, Ted <yuzhihong@gmail.com>:
>>>>> For hbase internal checksum, it is not in hbase 0.92.x release.
>>>>>
>>>>> Please use 0.94.2 or newer release.
>>>>>
>>>>> Thanks
>>>>>
>>>>> On Jan 27, 2013, at 2:29 PM, David Koch <ogdude@googlemail.com>
wrote:
>>>>>
>>>>>> Hello,
>>>>>>
>>>>>> I read about "short circuit reads" in the HBase documentation's
>>>>>> performance
>>>>>> section[1] and was wondering what people's experiences were using
>>>>>> this
>>>>>> in
>>>>>> a
>>>>>> production setting.
>>>>>>
>>>>>> Also,
>>>>>>
>>>>>> 1. Since only one dedicated user can take advantage of the feature
do
>>>>>> you
>>>>>> launch all jobs as this user?
>>>>>> 2. Can dfs.client.read.shortcircuit be set to false for jobs wich
are
>>>>>> not
>>>>>> launched by the short-circuit user in order to avoid exceptions?
In
>>>>>> other
>>>>>> words - can this setting be overriden by the client configuration's
>>>>>> hbase-site.xml?
>>>>>> 3. In the same context, it is suggested to enable HBase internal
>>>>>> checksums[2]. Is this a feature which can be enabled in HBase 0.92.1
>>>>>> which
>>>>>> is part of the Cloudera 4.1.x release?
>>>>>>
>>>>>> Thank you,
>>>>>>
>>>>>> /David
>>>>>>
>>>>>> [1] http://hbase.apache.org/book/perf.hdfs.html#ftn.d2145e7370
>>>>>> [2] https://issues.apache.org/jira/browse/HBASE-5074
>>>>>
>>>
>

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