3. Add HBase RegionServer

Use the following instructions to manually add HBase RegionServer hosts:

On each of the newly added slave nodes, install HBase and ZooKeeper.
- For RHEL/CentOS:
```
yum install zookeeper hbase
```
- For SLES:
```
zypper install zookeeper hbase                 
```

On each of the newly added slave nodes, add the HDP repository to yum:

wget -nv //public-repo-1.hortonworks.com/HDP-1.2.2/repos/centos6/hdp.repo -O
/etc/yum.repos.d/hdp.repo
yum clean all

Copy the HBase configurations to the newly added slave nodes and set appropriate permissions.

Option I: Copy HBase config files from an existing slave node.

On any existing slave node, make a copy of the current configurations:
```
tar zcvf hbase_conf.tgz /etc/hbase/conf  
tar zcvf zookeeper_conf.tgz /etc/zookeeper/conf            
```

Copy this file to each of the new nodes:

rm -rf /etc/hbase/conf
mkdir -p /etc/hbase/conf
cd /
tar zxvf $location_of_copied_conf_tar_file/hbase_conf.tgz
chmod -R 755 /etc/hbase/conf

rm -rf /etc/zookeeper/conf
mkdir -p /etc/zookeeper/conf
cd /
tar zxvf $location_of_copied_conf_tar_file/zookeeper_conf.tgz
chmod -R 755 /etc/zookeeper/conf

Option II: Manually add Hadoop configuration files.

Download the HBase/ZooKeeper config files from here and extract these files under configuration_files -> hbase and configuration_files -> zookeeper directories to two temporary locations.

Modify the configuration files:

Table 7.5. zoo.cfg
Variable	Example	Description
server.1	`$zookeeper.server1.full.hostname:2888:3888`	Enter the 1st ZooKeeper hostname
server.2	`$zookeeper.server1.full.hostname:2888:3888`	Enter the 2nd ZooKeeper hostname
server.3	`$zookeeper.server3.full.hostname:2888:3888`	Enter the 3rd ZooKeeper hostname

Table 7.6. hbase-site.xml
Variable	Example	Description
hbase.rootdir	`hdfs://$namenode.full.hostname:8020/apps/hbase/data`	Enter the HBase NameNode server
hbase.master.info.bindAddress	`$hbase.master.full.hostname`	Enter the HBase Master server hostname
hbase.zookeeper.quorum	`server1.full.hostname,server2.full.hostname, server3.full.hostname`	Comma separated list of Zookeeper servers (match to what is specified in `zoo.cfg` but without port numbers)

On all the new slave nodes create the config directory, copy all the config files, and set the permissions:
```
rm -r $HBASE_CONF_DIR ;
mkdir -p $HBASE_CONF_DIR ;
```
```
copy all the config files to $HBASE_CONF_DIR
```
```
chmod a+x $HBASE_CONF_DIR/;
chown -R $HBASE_USER:$HADOOP_GROUP $HBASE_CONF_DIR/../  ;
chmod -R 755 $HBASE_CONF_DIR/../
```
```
rm -r $ZOOKEEPER_CONF_DIR ;
mkdir -p $ZOOKEEPER_CONF_DIR ;
```
```
copy all the config files to $ZOOKEEPER_CONF_DIR 
```
```
chmod a+x $ZOOKEEPER_CONF_DIR/;
chown -R $ZOOKEEPER_USER:$HADOOP_GROUP $ZOOKEEPER_CONF_DIR/../  ;
chmod -R 755 $ZOOKEEPER_CONF_DIR/../
                
```
where:
- $HBASE_CONF_DIR is the directory to store the HBase configuration files. For example, /etc/hbase/conf.
- $HBASE_USER is the user owning the HBase services. For example, hbase.
- $HADOOP_GROUP is a common group shared by services. For example, hadoop.
- $ZOOKEEPER_CONF_DIR is the directory to store the ZooKeeper configuration files. For example, /etc/zookeeper/conf
- $ZOOKEEPER_USER is the user owning the ZooKeeper services. For example, zookeeper.

Start HBase RegionServer node:

<login as $HBASE_USER>
/usr/lib/hbase/bin/hbase-daemon.sh --config $HBASE_CONF_DIR start regionserver

On the HBase Master host machine, edit the /usr/lib/hbase/conf file and add the list of slave nodes' hostnames. The hostnames must be separated by a newline character.
Optional: Enable monitoring on the newly added slave nodes using the instructions provided here.
Optional: Enable cluster alerting on the newly added slave nodes using the instructions provided here.

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