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HBase, mail # user - Short-circuit reads


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David Koch 2013-01-27, 22:29
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Jean-Daniel Cryans 2013-01-27, 22:45
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Ted 2013-01-27, 22:34
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Jean-Marc Spaggiari 2013-01-27, 22:38
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Jean-Daniel Cryans 2013-01-27, 22:50
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Jean-Marc Spaggiari 2013-01-27, 22:55
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Re: Short-circuit reads
David Koch 2013-01-27, 23:16
Alright, thanks for the replies - I'll do some testing.

/David

On Sun, Jan 27, 2013 at 11:55 PM, Jean-Marc Spaggiari <
[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]>:
> > On Sun, Jan 27, 2013 at 2:38 PM, Jean-Marc Spaggiari
> > <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]>:
> >>> 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 <[EMAIL PROTECTED]> 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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Jean-Daniel Cryans 2013-01-28, 02:56
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Jean-Marc Spaggiari 2013-01-28, 12:45
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Ted Yu 2013-01-27, 22:45