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From Andrew Purtell <apurt...@apache.org>
Subject Re: read short circuit
Date Thu, 13 Sep 2012 17:44:20 GMT
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 <nkeywal@gmail.com> 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 <jdcryans@apache.org>wrote:
>
>> On Thu, Sep 13, 2012 at 7:58 AM, n keywal <nkeywal@gmail.com> 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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