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Date: Fri, 3 Jun 2011 04:47:10 -0700 (PDT)
From: Andrew Purtell <apurtell@apache.org>
Reply-To: apurtell@apache.org
Subject: Re: Does Hadoop 0.20.2 and HBase 0.90.3 compatible ??
To: common-user@hadoop.apache.org, user@hbase.apache.org
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> Is *Hadoop 0.20.2=A0 also not compatible with Hbase 0.90.3 ???*=0A=0AIn a=
 strict sense they are, but without append support HBase cannot guarantee t=
hat the last block of write ahead logs are synced to disk, so in some failu=
re cases edits will be lost. With append support then the "hole" of these f=
ailure cases is closed. Also append branch adds a change to lease recovery =
that allows the HBase Master to take ownership of regionserver logs in orde=
r to split them quickly. (Without this patch you may be waiting 10 minutes =
for lease recovery...) So these differences are clearly important for durab=
ility and fault recovery in a realistic time frame.=0A=0AA full reinstallat=
ion is not necessary.=0A=0AYou can take the Hadoop core jar packaged in lib=
/ of HBase 0.90.3 and replace every Hadoop core jar on your cluster with th=
em.=0A=0AOR =0A=0AYou can compile 0.20-append and just replace the Hadoop c=
ore jar everywhere with the result, including the one in the HBase lib/.=0A=
=0A   - Andy=0A=0A--- On Fri, 6/3/11, praveenesh kumar <praveenesh@gmail.co=
m> wrote:=0A=0A> From: praveenesh kumar <praveenesh@gmail.com>=0A> Subject:=
 Does Hadoop 0.20.2 and HBase 0.90.3 compatible ??=0A> To: common-user@hado=
op.apache.org, user@hbase.apache.org=0A> Date: Friday, June 3, 2011, 3:37 A=
M=0A> Guys,=0A> =0A> I am in a very big big confusion. Please.. I really ne=
ed=0A> your feedbacks and=0A> suggestions..=0A> =0A> The scenario is like t=
his...=0A> =0A> I set up *Hadoop 0.20.2 cluster* of *12 nodes*..=0A> =0A> N=
ow I set up* Hbase 0.90.3*=A0 *12 node cluster* on top=0A> of it.=0A> =0A> =
But after all that experimenting and struggling.. I read=0A> the following =
SHOCKING line on my Hbase web UI=0A> =0A> ---* " You are currently running =
the HMaster without HDFS append support=0A> enabled. This may result in dat=
a loss. Please see the HBase wiki for=0A> details. "*=0A> =0A> And when I s=
earched more about it.. I found Michael G. Nolls article..=0A> saying that =
*Hadoop 0.20.2 and Hbase 0.90.2 are not compatible*.=0A> =0A> Is *Hadoop 0.=
20.2=A0 also not compatible with Hbase 0.90.3 ???*=0A> =0A> So does=A0 it m=
eans I have to re-install hadoop 0.20.=0A> append if I want to use Hbase.=
=0A> =0A> I did a lot of struggle to reach upto this stage.. do I=0A> have =
to do all of it again.. ??=0A> =0A> Is there any other work around solution=
.. of not=0A> re-installing everything again ??=0A> =0A> Please help..!!!=
=A0 :-(=0A> =0A> Thanks,=0A> Praveenesh=0A>