4. Optional - Configure Monitoring Using Ganglia

For each of the newly added slave node, complete the following instructions in order to use Ganglia for monitoring and metrics collection:

On each new host, install the Ganglia gmond:

Copy the HDP Ganglia scripts from any existing slave node to the newly added node:

mkdir -p /usr/libexec/hdp/ganglia
scp root@$FQDN_of_any_existing_node:/usr/libexec/hdp/ganglia/*
/usr/libexec/hdp/ganglia

Configure the gmond emitter:

/usr/libexec/hdp/ganglia/setupGanglia.sh -c HDPSlaves

Edit the /etc/ganglia/hdp/HDPSlaves/conf.d/gmond.slave.confto validate the slave configuration files.
Ensure that host points to the Ganglia server master node as shown below:
```
host = $Ganglia_server_hostname
```
Copy Ganglia service start file from any existing slave node to each of the newly added node:
```
scp root@$existing_node:/etc/init.d/hdp-gmond /etc/init.d
/etc/init.d/hdp-gmond start
```
This step will start Ganglia monitoring for your Hadoop cluster.