Cluster Server 7.4.1 Administrator's Guide - Linux
- Section I. Clustering concepts and terminology
- Introducing Cluster Server
- About Cluster Server
- About cluster control guidelines
- About the physical components of VCS
- Logical components of VCS
- Types of service groups
- About resource monitoring
- Agent classifications
- About cluster control, communications, and membership
- About security services
- Components for administering VCS
- About cluster topologies
- VCS configuration concepts
- Introducing Cluster Server
- Section II. Administration - Putting VCS to work
- About the VCS user privilege model
- Administering the cluster from the command line
- About administering VCS from the command line
- About installing a VCS license
- Administering LLT
- Starting VCS
- Stopping the VCS engine and related processes
- Logging on to VCS
- About managing VCS configuration files
- About managing VCS users from the command line
- About querying VCS
- About administering service groups
- Modifying service group attributes
- About administering resources
- Enabling and disabling IMF for agents by using script
- Linking and unlinking resources
- About administering resource types
- About administering clusters
- Configuring applications and resources in VCS
- VCS bundled agents for UNIX
- Configuring NFS service groups
- About NFS
- Configuring NFS service groups
- Sample configurations
- About configuring the RemoteGroup agent
- About configuring Samba service groups
- About testing resource failover by using HA fire drills
- Predicting VCS behavior using VCS Simulator
- Section III. VCS communication and operations
- About communications, membership, and data protection in the cluster
- About cluster communications
- About cluster membership
- About membership arbitration
- About membership arbitration components
- About server-based I/O fencing
- About majority-based fencing
- About the CP server service group
- About secure communication between the VCS cluster and CP server
- About data protection
- Examples of VCS operation with I/O fencing
- About cluster membership and data protection without I/O fencing
- Examples of VCS operation without I/O fencing
- Administering I/O fencing
- About the vxfentsthdw utility
- Testing the coordinator disk group using the -c option of vxfentsthdw
- About the vxfenadm utility
- About the vxfenclearpre utility
- About the vxfenswap utility
- About administering the coordination point server
- About configuring a CP server to support IPv6 or dual stack
- About migrating between disk-based and server-based fencing configurations
- Migrating between fencing configurations using response files
- Controlling VCS behavior
- VCS behavior on resource faults
- About controlling VCS behavior at the service group level
- About AdaptiveHA
- Customized behavior diagrams
- About preventing concurrency violation
- VCS behavior for resources that support the intentional offline functionality
- VCS behavior when a service group is restarted
- About controlling VCS behavior at the resource level
- VCS behavior on loss of storage connectivity
- Service group workload management
- Sample configurations depicting workload management
- The role of service group dependencies
- About communications, membership, and data protection in the cluster
- Section IV. Administration - Beyond the basics
- VCS event notification
- VCS event triggers
- Using event triggers
- List of event triggers
- Virtual Business Services
- Section V. Veritas High Availability Configuration wizard
- Introducing the Veritas High Availability Configuration wizard
- Administering application monitoring from the Veritas High Availability view
- Administering application monitoring from the Veritas High Availability view
- Administering application monitoring from the Veritas High Availability view
- Section VI. Cluster configurations for disaster recovery
- Connecting clusters–Creating global clusters
- VCS global clusters: The building blocks
- About global cluster management
- About serialization - The Authority attribute
- Prerequisites for global clusters
- Setting up a global cluster
- About IPv6 support with global clusters
- About cluster faults
- About setting up a disaster recovery fire drill
- Test scenario for a multi-tiered environment
- Administering global clusters from the command line
- About global querying in a global cluster setup
- Administering clusters in global cluster setup
- Setting up replicated data clusters
- Setting up campus clusters
- Connecting clusters–Creating global clusters
- Section VII. Troubleshooting and performance
- VCS performance considerations
- How cluster components affect performance
- How cluster operations affect performance
- VCS performance consideration when a system panics
- About scheduling class and priority configuration
- VCS agent statistics
- About VCS tunable parameters
- Troubleshooting and recovery for VCS
- VCS message logging
- Gathering VCS information for support analysis
- Troubleshooting the VCS engine
- Troubleshooting Low Latency Transport (LLT)
- Troubleshooting Group Membership Services/Atomic Broadcast (GAB)
- Troubleshooting VCS startup
- Troubleshooting issues with systemd unit service files
- Troubleshooting service groups
- Troubleshooting resources
- Troubleshooting sites
- Troubleshooting I/O fencing
- Fencing startup reports preexisting split-brain
- Troubleshooting CP server
- Troubleshooting server-based fencing on the VCS cluster nodes
- Issues during online migration of coordination points
- Troubleshooting notification
- Troubleshooting and recovery for global clusters
- Troubleshooting licensing
- Licensing error messages
- Troubleshooting secure configurations
- Troubleshooting wizard-based configuration issues
- Troubleshooting issues with the Veritas High Availability view
- VCS message logging
- VCS performance considerations
- Section VIII. Appendixes
Example: Four-system cluster where cluster interconnect fails
In this example, the cluster interconnect fails in such a way as to split the cluster from one four-system cluster to two-system clusters. The cluster performs membership arbitration to ensure that only one subcluster remains.
Due to loss of heartbeat, System0 and System1 both believe System2 and System3 are down. System2 and System3 both believe System0 and System1 are down.
The progression of I/O fencing operations are as follows:
LLT on each of the four systems no longer receives heartbeat messages from the systems on the other side of the interconnect failure on any of the configured LLT interfaces for the peer inactive timeout configured time.
LLT on each system passes to GAB that it has noticed a membership change. Specifically:
LLT on System0 passes to GAB that it no longer sees System2 and System3
LLT on System1 passes to GAB that it no longer sees System2 and System3
LLT on System2 passes to GAB that it no longer sees System0 and System1
LLT on System3 passes to GAB that it no longer sees System0 and System1
After LLT informs GAB of a heartbeat loss, the systems that are remaining do a "GAB Stable Timeout" (5 seconds). In this example:
System0 and System1 agree that both of them do not see System2 and System3
System2 and System3 agree that both of them do not see System0 and System1
GAB marks the system as DOWN, and excludes the system from the cluster membership. In this example:
GAB on System0 and System1 mark System2 and System3 as DOWN and excludes them from cluster membership.
GAB on System2 and System3 mark System0 and System1 as DOWN and excludes them from cluster membership.
GAB on each of the four systems passes the membership change to the vxfen driver for membership arbitration. Each subcluster races for control of the coordinator disks. In this example:
System0 has the lower LLT ID, and races on behalf of itself and System1.
System2 has the lower LLT ID, and races on behalf of itself and System3.
GAB on each of the four systems also passes the membership change to HAD. HAD waits for the result of the membership arbitration from the fencing module before taking any further action.
If System0 is not able to reach a majority of the coordination points, then the VxFEN driver will initiate a racer re-election from System0 to System1 and System1 will initiate the race for the coordination points.
Assume System0 wins the race for the coordinator disks, and ejects the registration keys of System2 and System3 off the disks. The result is as follows:
System0 wins the race for the coordinator disk. The fencing module on System0 sends a WON_RACE to all other fencing modules in the current cluster, in this case System0 and System1. On receiving a WON_RACE, the fencing module on each system in turn communicates success to HAD. System0 and System1 remain valid and current members of the cluster.
If System0 dies before it sends a WON_RACE to System1, then VxFEN will initiate a racer re-election from System0 to System1 and System1 will initiate the race for the coordination points.
System1 on winning a majority of the coordination points remains valid and current member of the cluster and the fencing module on System1 in turn communicates success to HAD.
System2 loses the race for control of the coordinator disks and the fencing module on System 2 sends a LOST_RACE message. The fencing module on System2 calls a kernel panic and the system restarts.
System3 sees another membership change from the kernel panic of System2. Because that was the system that was racing for control of the coordinator disks in this subcluster, System3 also panics.
HAD carries out any associated policy or recovery actions based on the membership change.
System2 and System3 are blocked access to the shared storage (if the shared storage was part of a service group that is now taken over by System0 or System 1).
To rejoin System2 and System3 to the cluster, the administrator must do the following:
Shut down System2 and System3
Fix the cluster interconnect links
Restart System2 and System3