1. LAB: Managing Services July 2012
LAB: Managing Services
Goal
In these exercises you will view which services are running, start and stop services,
start and stop the Warden, and (if appropriate) simulate a service failover.
Exercise: Managing Services
Connect to your MCS for your cluster
On the Dashboard, scroll down until you can see the Services panel on the
right-hand side
o Notice that you can see the total number of each service running in
the entire cluster
o You can also click on any of the number or service names to drill down
into the details of that service
Scroll back to the top of the Dashboard and click on the name of the cluster in
the heat map
Click on the name of your node and scroll down to the Manage Node Services
section on the right-hand side
o Notice that you can view the status of the services running on your
node and also stop, start, restart and view log data for the service
Connect to your node via ssh
Use jps to view the running MapR services
Unless your node is running a production job, use the CLI to stop the
TaskTracker running on your node
o mapcli node services -tasktracker stop -nodes
<node_name>
Use jps to view the running MapR services
o You should now notice that the TaskTracker is no longer running
Use the CLI to start the TaskTracker on your node
o You can modify the CLI syntax from above
Exercise: Stop and Start the Warden
Connect to your node via ssh
Use jps to view the running MapR services
Unless your node is running a production job, stop the Warden service on
your node
o /etc/init.d/mapr-warden stop
Use jps to view the running MapR services
Start the Warden service on your node
o You can modify the syntax from above
Use jps to view the running MapR services
© 2012 by MapR Technologies Page 1 of 2

2. LAB: Managing Services July 2012
Exercise: Failover
This exercise will be performed as a group and demonstrated by the instructor.
You will stop the Warden on a node where the CLDB/JobTracker are running.
This will effectively eliminate that node from the cluster and cause a failover of
its critical services.
First, ensure that there are no production jobs running on the cluster
In order to view the failover in action, you may wish to run the Web Server
on a different node than the one on which you are stopping the Warden
Once you have a Web Server node separate from the simulated fail node,
connect a web browser to the Web Server node
On the simulated fail node, stop the Warden using the syntax from above
Watch the Dashboard to observe the failover happen. You should be able to
see other nodes taking over the services that are no longer available on the
simulated fail node.
© 2012 by MapR Technologies Page 2 of 2