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Date: Wed, 9 Jul 2014 14:25:58 -0700
From: lars hofhansl <larsh@apache.org>
Reply-To: lars hofhansl <larsh@apache.org>
Subject: Re: HBase Upgrade from 0.94.x to 0.98.x: How to do rollback?
To: "user@hbase.apache.org" <user@hbase.apache.org>
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Not sure many people have tried that here. Sounds like it should work, thou=
gh.=0A=0A=0AAny chance you could set up a single node cluster (i.e. run a s=
ingle node HDFS and HBase on the same machine) and try?=0AShould not be har=
d to setup, and would be valuable for folks here to know.=0A=0A=0A-- Lars=
=0A=0A=0A=0A________________________________=0A From: Kiran Kumar.M.R <Kira=
n.Kumar.MR@huawei.com>=0ATo: "user@hbase.apache.org" <user@hbase.apache.org=
> =0ASent: Wednesday, July 9, 2014 1:42 PM=0ASubject: HBase Upgrade from 0.=
94.x to 0.98.x: How to do rollback?=0A =0A=0AHi,=0AWe are proposing upgrade=
 solution to one of our customers.=0A=0ACurrent Version:=A0 Hadoop 2.0.1+Hb=
ase 0.94.11+ ZK=0AUpgrade Version: Hadoop 2.3+HBase 0.98 +ZK=0A=0ACurrent C=
luster Setup:=A0 =A0 with 50+ nodes storing 300TB of HBase data=0AAll compo=
nents are installed under $HADOOP_V1.=0ANN, DN and ZK directories are exter=
nal.=0A=0AMain requirement is that customer wants to rollback to old versio=
n in case of any failures during the upgrade.=0AHDFS provides rollback opti=
on. HBase has no rollback option. To overcome this, I am thinking of runnin=
g HBase upgrade under hdfs -upgrade step.=0A=0ADetailed steps are given bel=
ow:=0A=0A1.=A0 =A0 =A0 Shutdown $HADOOP_V1 cluster=0A=0A2.=A0 =A0 =A0 Take =
backup of $NN_DR and $ZK_DIR=0A=0A3.=A0 =A0 =A0 Install new version (Hadoop=
 2.3+HBase 0.98 +ZK) under new directory on same nodes i.e $HADOOP_V2=0A=0A=
4.=A0 =A0 =A0 Configure it to use existing folders $NN_DIR, $DN_DIR, $ZK_DI=
R=0A=0A5.=A0 =A0 =A0 Start Zk=0A=0A6.=A0 =A0 =A0 Start hdfs with -upgrade o=
ption=0A=0A7.=A0 =A0 =A0 Start hbase upgrade tool=A0 "$ bin/hbase upgrade -=
execute"=0A=0A8.=A0 =A0 =A0 In case of any failure do rollback=0A=0Aa.=A0 =
=A0 =A0 HDFS rollback=0A=0Ab.=A0 =A0 =A0 Stop ZK and recover old ZK data ba=
ckup to ZK_DIR=0A=0Ac.=A0 =A0 =A0 Start old version $HA DOOP_V1 (HBase 0.94=
 should work as HDFS rollback should revert namespace and other changes don=
e by meta data tool)=0A=0A9.=A0 =A0 =A0 If HBase upgrade is fine, finalize =
upgrade=0A=0Aa.=A0 =A0 =A0 HDFS finalizeUpgrade=0A=0Ab.=A0 =A0 =A0 Delete o=
ld version=0A=0AI am mainly concerned about step 8, is this rollback expect=
ed to work?=0AAre there any better alternatives to do HBase rollback.=0A=0A=
Regards,=0AKiran
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