High availability RH Cluster solution

1. RedHat Cluster
High-Availability
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

2. RedHat Cluster
● Cluster
● Storage
● High Availability Overview
● Quorum
● Fencing
● Resources and Services
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

3. Cluster
● Load-balancing
● Compute
● High-availability
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

4. Storage
● Types of data
– System data versus user data
– Static data versus dynamic data
– Current data versus archived data
– etc.
● Storage technologies
– Direct atached storage
– Shared storage
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

5. RedHat Storage Model
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

6. ISCSI and FibreChannel
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

7. Multipathing
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

8. High Availibility Overwiew
● Failover
● Storage
● Non-Goals
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

9. Hardware
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

10. Hardware
● Cluster Nodes
● Public Network
● Private Network
● Networked Power Switch
● Fibre Channel Switch
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

11. Software
● corosync
● cman
● fenced
● modclusterd
● rgmanager
● dlm
● clvmd
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

12. Software
● ricci (Conga project)
● oddjobd
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

13. Requirements
● Number of nodes up to 16
● Single Site – not multiple physical location
● Supported Fencing Hardware – power, storage
● ACPI
● NetworkManager is not compatabile
● SELinux is fully supported
● Network - 5404-5/UDP,21064/TCP,16861/TCP
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

14. Quorum
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

15. Calculating Quorum
● Expected votes
● Total votes
● Quorum = floor(expected votes / 2 + 1)
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

16. Displaying Quorum
● /etc/cluster/cluster.conf
– <clusternode name=....... votes=“2“/>
● ccs_tool lsnode
● cman_tool status
● clustat
● clustat -Q && echo Quorate || echo Not Quorate
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

17. Fencing
● What is fencing
● Power fencing
● Fabric fencing
● Other fencing
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

18. Power fencing
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

19. Fabric fencing
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

20. Resources and Services
● Resources
● Resource Groups (Services)
● rgmanager
● Failover domains
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

21. Failover Domains
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

22. Failover Domain Settings
● Prioritized
● Restricted
● No Failback
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

23. Service Group Options
● Name
● Automatically Start This Service
● Run Exclusive
● Fialover Domain
● Recover Policy
– Restart
– Restart-Disable
– Relocate
– Disable
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

24. Dependency Trees
● /usr/share/cluster/service.sh
<special tag="rgmanager">
<attributes maxinstances="1"/>
<child type="lvm" start="1" stop="9"/>
<child type="fs" start="2" stop="8"/>
<child type="clusterfs" start="3" stop="7"/>
<child type="netfs" start="4" stop="6"/>
<child type="nfsexport" start="5" stop="5"/>
<child type="nfsclient" start="6" stop="4"/>
<child type="ip" start="7" stop="2"/>
<child type="smb" start="8" stop="3"/>
<child type="script" start="9" stop="1"/>
</special>
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

25. Dependency Trees
● cluster.conf
<service domain=.............>
<fs ref=“myfs“>
<apache ref=“myapache“/>
</fs>
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz

26. Documentation
http://access.redhat.com/knowledge/docs
Red Hat Enterprise Linux
– Cluster Administration
– High Availibility
– Fence Configuration
Elos technologies
U Kanálky 1559/5, 120 00 Praha 2
http://www.elostech.cz