1. Managing Services
7/6/2012
© 2012 MapR Technologies Managing Services 1

2. Managing Services
Agenda
• Review: What are Services?
• Exercise: Managing Services
• The Warden
• Exercise: Stop and Start the Warden
• Service Failover
• Exercise: Failover
• Best Practices
© 2012 MapR Technologies Managing Services 2

3. Managing Services
Objectives
At the end of this module you will be able to:
• Identify the different MapR services
• Describe the function that each MapR service provides
• See which services are running on a node
• Describe the purpose of the Warden
• Explain how service failover works
• List the best practices for running MapR services
© 2012 MapR Technologies Managing Services 3

4. Review: What are
Services?
© 2012 MapR Technologies Managing Services 4

5. What Are Services?
 Services implement roles
fulfilled by a node
 Administrative services:
– ZooKeeper CLDB, JobTracker, NFS,
etc.
 Processing services:
– TaskTracker, FileServer, Hbase, etc.
 Application services:
– Distinct from scripts or run-at-will
applications like Pig
A daemon called the Warden manages services
© 2012 MapR Technologies Managing Services 5

6. Managing Services
 Monitoring
 JPS/PS
 MapR CLI/RESTful API
 MCS Dashboard
 Starting/stopping
 Failover
© 2012 MapR Technologies Managing Services 6

7. Exercise:
Managing Services
© 2012 MapR Technologies Managing Services 7

8. See What is Running
 MCS Dashboard
 jps/ps
 maprcli dashboard info
© 2012 MapR Technologies Managing Services 8

9. Start, Stop, Restart Services
 MapR Control System
 maprcli node services
-service action (start, stop, restart)
 optional
maprcli node services
-action action
-name name
-h to get help
These mechanisms use the warden
© 2012 MapR Technologies Managing Services 9

10. The Warden
© 2012 MapR Technologies Managing Services 10

11. The Warden
 Knows what should be running
and allocates memory:
warden.conf
 /opt/mapr/roles used to
determine services when
configure.sh is run
 Manages services and HA for
services
© 2012 MapR Technologies Managing Services 11

12. Exercise:
Stop and Start the
Warden
© 2012 MapR Technologies Managing Services 12

13. Start/Stop/Restart the Warden
 /etc/init.d/mapr-warden stop
 /etc/init.d/mapr-warden start
 /etc/init.d/mapr-warden restart
© 2012 MapR Technologies Managing Services 13

14. Service Failover
© 2012 MapR Technologies Managing Services 14

15. Failover
CLDB Warm Standby
Run at will Pig
Followers
ZK
(With a minimum)
Hot spares
NFS
(no minimum)
JT Cold standby
ZooKeeper and NFS are actually more complex
© 2012 MapR Technologies Managing Services 15

16. Exercise:
Failover
© 2012 MapR Technologies Managing Services 16

17. Failover
Let’s kill a node and see what happens!
© 2012 MapR Technologies Managing Services 17

18. Best Practices
© 2012 MapR Technologies Managing Services 18

19. Best Practices
 Depends on the size of your cluster and load
 In general, avoid running compute-intensive services on the same
node
 Some suggestions:
– Avoid running ZooKeeper and CLDB together
– If you run TaskTracker on CLDB or ZK nodes, reduce slots
– Avoid running the active JobTracker on the primary CLDB node
– Avoid running the active JobTracker on ZK nodes
© 2012 MapR Technologies Managing Services 19

20. Questions
© 2012 MapR Technologies Managing Services 20