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HBase, mail # dev - read short circuit


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n keywal 2012-09-13, 14:58
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Jean-Daniel Cryans 2012-09-13, 16:30
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n keywal 2012-09-13, 16:42
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Re: read short circuit
Andrew Purtell 2012-09-13, 17:44
Making it the default seems reasonable.

For <= 0.94, the security profile has a separate hbase-site.xml file
under test resources where there it could be defaulted as off.  Reason
is the local block sharing requires some shared group membership
between HBase and HDFS service accounts that might be objectionable in
a secure setting. So we should have test coverage with it off.

On Thu, Sep 13, 2012 at 9:42 AM, n keywal <[EMAIL PROTECTED]> wrote:
> It's all in the "pretty much" :-)
> Should we make it the default (i.e. recommending it in the doc, emitting a
> warning if it's not set) for all installation ?
> Or would it make sense to separate the store and wal cases, meaning that we
> need a change in hdfs to make this possible?
>
>
> On Thu, Sep 13, 2012 at 6:30 PM, Jean-Daniel Cryans <[EMAIL PROTECTED]>wrote:
>
>> On Thu, Sep 13, 2012 at 7:58 AM, n keywal <[EMAIL PROTECTED]> wrote:
>> > Hi,
>> >
>> > Is there any known counter indication for read short circuit?
>> > I had a look at JD's presentation from January. It was tested vs. HBase
>> as
>> > a whole; and still recommended for nearly all cases.
>>
>> Pretty much.
>>
>> >
>> > We could make it at least the default when reading HLog files (even if it
>> > seems it's a 'per client" config, there is may be something to look at as
>> > well)?
>>
>> You have to add 2 configs in hdfs-site.xml, which we can't do from HBase.
>>
>> J-D
>>

--
Best regards,

   - Andy

Problems worthy of attack prove their worth by hitting back. - Piet
Hein (via Tom White)
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Jesse Yates 2012-09-13, 17:57
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Andrew Purtell 2012-09-13, 18:31
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n keywal 2012-09-13, 19:17
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Andrew Purtell 2012-09-13, 20:20
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n keywal 2012-09-13, 20:34
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Andrew Purtell 2012-09-13, 21:07
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n keywal 2012-09-14, 12:48
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Jean-Daniel Cryans 2012-09-13, 16:51
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Andrew Purtell 2012-09-13, 17:46
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Stack 2012-09-13, 17:28
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Jean-Daniel Cryans 2012-09-13, 18:01