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
- About resources and resource dependencies
- Categories of resources
- About resource types
- About service groups
- Types of service groups
- About the ClusterService group
- About the cluster UUID
- About agents in VCS
- About agent functions
- About resource monitoring
- Agent classifications
- VCS agent framework
- About cluster control, communications, and membership
- About security services
- Components for administering VCS
- Putting the pieces together
- 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
- Administering the AMF kernel driver
- Starting VCS
- Stopping 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
- Adding and deleting service groups
- Modifying service group attributes
- Bringing service groups online
- Taking service groups offline
- Switching service groups
- Migrating service groups
- Freezing and unfreezing service groups
- Enabling and disabling service groups
- Enabling and disabling priority based failover for a service group
- Clearing faulted resources in a service group
- Flushing service groups
- Linking and unlinking service groups
- Administering agents
- About administering resources
- About adding resources
- Adding resources
- Deleting resources
- Adding, deleting, and modifying resource attributes
- Defining attributes as local
- Defining attributes as global
- Enabling and disabling intelligent resource monitoring for agents manually
- Enabling and disabling IMF for agents by using script
- Linking and unlinking resources
- Bringing resources online
- Taking resources offline
- Probing a resource
- Clearing a resource
- About administering resource types
- Administering systems
- About administering clusters
- Configuring and unconfiguring the cluster UUID value
- Retrieving version information
- Adding and removing systems
- Changing ports for VCS
- Setting cluster attributes from the command line
- About initializing cluster attributes in the configuration file
- Enabling and disabling secure mode for the cluster
- Migrating from secure mode to secure mode with FIPS
- Using the -wait option in scripts that use VCS commands
- Running HA fire drills
- About administering simulated clusters from the command line
- Configuring applications and resources in VCS
- Configuring resources and applications
- VCS bundled agents for UNIX
- Configuring NFS service groups
- About NFS
- Configuring NFS service groups
- Sample configurations
- Sample configuration for a single NFS environment without lock recovery
- Sample configuration for a single NFS environment with lock recovery
- Sample configuration for a single NFSv4 environment
- Sample configuration for a multiple NFSv4 environment
- Sample configuration for a multiple NFS environment without lock recovery
- Sample configuration for a multiple NFS environment with lock recovery
- Sample configuration for configuring NFS with separate storage
- Sample configuration when configuring all NFS services in a parallel service group
- About configuring the RemoteGroup agent
- About configuring Samba service groups
- Configuring the Coordination Point agent
- 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 making CP server highly available
- About the CP server database
- Recommended CP server configurations
- About the CP server service group
- About the CP server user types and privileges
- About secure communication between the VCS cluster and CP server
- About data protection
- About I/O fencing configuration files
- 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
- Summary of best practices for cluster communications
- Administering I/O fencing
- About administering I/O fencing
- About the vxfentsthdw utility
- General guidelines for using the vxfentsthdw utility
- About the vxfentsthdw command options
- Testing the coordinator disk group using the -c option of vxfentsthdw
- Performing non-destructive testing on the disks using the -r option
- Testing the shared disks using the vxfentsthdw -m option
- Testing the shared disks listed in a file using the vxfentsthdw -f option
- Testing all the disks in a disk group using the vxfentsthdw -g option
- Testing a disk with existing keys
- Testing disks with the vxfentsthdw -o option
- About the vxfenadm utility
- About the vxfenclearpre utility
- About the vxfenswap utility
- About administering the coordination point server
- CP server operations (cpsadm)
- Cloning a CP server
- Adding and removing VCS cluster entries from the CP server database
- Adding and removing a VCS cluster node from the CP server database
- Adding or removing CP server users
- Listing the CP server users
- Listing the nodes in all the VCS clusters
- Listing the membership of nodes in the VCS cluster
- Preempting a node
- Registering and unregistering a node
- Enable and disable access for a user to a VCS cluster
- Starting and stopping CP server outside VCS control
- Checking the connectivity of CP servers
- Adding and removing virtual IP addresses and ports for CP servers at run-time
- Taking a CP server database snapshot
- Replacing coordination points for server-based fencing in an online cluster
- Refreshing registration keys on the coordination points for server-based fencing
- About configuring a CP server to support IPv6 or dual stack
- Deployment and migration scenarios for CP server
- About migrating between disk-based and server-based fencing configurations
- Migrating from disk-based to server-based fencing in an online cluster
- Migrating from server-based to disk-based fencing in an online cluster
- Migrating between fencing configurations using response files
- Sample response file to migrate from disk-based to server-based fencing
- Sample response file to migrate from server-based fencing to disk-based fencing
- Sample response file to migrate from single CP server-based fencing to server-based fencing
- Response file variables to migrate between fencing configurations
- Enabling or disabling the preferred fencing policy
- About I/O fencing log files
- Controlling VCS behavior
- VCS behavior on resource faults
- About controlling VCS behavior at the service group level
- About the AutoRestart attribute
- About controlling failover on service group or system faults
- About defining failover policies
- About AdaptiveHA
- About system zones
- About sites
- Load-based autostart
- About freezing service groups
- About controlling Clean behavior on resource faults
- Clearing resources in the ADMIN_WAIT state
- About controlling fault propagation
- 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
- Changing agent file paths and binaries
- 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
- About VCS event triggers
- Using event triggers
- List of event triggers
- About the dumptunables trigger
- About the globalcounter_not_updated trigger
- About the injeopardy event trigger
- About the loadwarning event trigger
- About the nofailover event trigger
- About the postoffline event trigger
- About the postonline event trigger
- About the preonline event trigger
- About the resadminwait event trigger
- About the resfault event trigger
- About the resnotoff event trigger
- About the resrestart event trigger
- About the resstatechange event trigger
- About the sysoffline event trigger
- About the sysup trigger
- About the sysjoin trigger
- About the unable_to_restart_agent event trigger
- About the unable_to_restart_had event trigger
- About the violation event trigger
- 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
- Understanding the Veritas High Availability view
- To view the status of configured applications
- To configure or unconfigure application monitoring
- To start or stop applications
- To suspend or resume application monitoring
- To switch an application to another system
- To add or remove a failover system
- To clear Fault state
- To resolve a held-up operation
- To determine application state
- To remove all monitoring configurations
- To remove VCS cluster configurations
- Administering application monitoring settings
- Administering application monitoring from the Veritas High Availability view
- Section VI. Cluster configurations for disaster recovery
- Connecting clusters–Creating global clusters
- How VCS global clusters work
- VCS global clusters: The building blocks
- Visualization of remote cluster objects
- About global service groups
- About global cluster management
- About serialization - The Authority attribute
- About resiliency and "Right of way"
- VCS agents to manage wide-area failover
- About the Steward process: Split-brain in two-cluster global clusters
- Secure communication in global clusters
- Prerequisites for global clusters
- About planning to set up global clusters
- Setting up a global cluster
- About IPv6 support with global clusters
- About cluster faults
- About setting up a disaster recovery fire drill
- Multi-tiered application support using the RemoteGroup agent in a global environment
- Test scenario for a multi-tiered environment
- Administering global clusters from the command line
- About administering global clusters from the command line
- About global querying in a global cluster setup
- Administering global service groups in a global cluster setup
- Administering resources in a global cluster setup
- Administering clusters in global cluster setup
- Administering heartbeats in a 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 booting a cluster system
- VCS performance consideration when a resource comes online
- VCS performance consideration when a resource goes offline
- VCS performance consideration when a service group comes online
- VCS performance consideration when a service group goes offline
- VCS performance consideration when a resource fails
- VCS performance consideration when a system fails
- VCS performance consideration when a network link fails
- VCS performance consideration when a system panics
- VCS performance consideration when a service group switches over
- VCS performance consideration when a service group fails over
- About scheduling class and priority configuration
- VCS agent statistics
- About VCS tunable parameters
- Troubleshooting and recovery for VCS
- VCS message logging
- Log unification of VCS agent's entry points
- Enhancing First Failure Data Capture (FFDC) to troubleshoot VCS resource's unexpected behavior
- GAB message logging
- Enabling debug logs for agents
- Enabling debug logs for IMF
- Enabling debug logs for the VCS engine
- Enable VCS logging for VxAT
- About debug log tags usage
- Gathering VCS information for support analysis
- Gathering LLT and GAB information for support analysis
- Gathering IMF information for support analysis
- Message catalogs
- 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
- If a unit service has failed and the corresponding module is still loaded, systemd cannot unload it and so its package cannot be removed
- If a unit service is active and the corresponding process is stopped outside of systemd, the service cannot be started again using 'systemctl start'
- If a unit service takes longer than the default timeout to stop or start the corresponding service, it goes into the Failed state
- Troubleshooting Intelligent Monitoring Framework (IMF)
- Troubleshooting service groups
- VCS does not automatically start service group
- System is not in RUNNING state
- Service group not configured to run on the system
- Service group not configured to autostart
- Service group is frozen
- Failover service group is online on another system
- A critical resource faulted
- Service group autodisabled
- Service group is waiting for the resource to be brought online/taken offline
- Service group is waiting for a dependency to be met.
- Service group not fully probed.
- Service group does not fail over to the forecasted system
- Service group does not fail over to the BiggestAvailable system even if FailOverPolicy is set to BiggestAvailable
- Restoring metering database from backup taken by VCS
- Initialization of metering database fails
- Error message appears during service group failover or switch
- Troubleshooting resources
- Troubleshooting sites
- Troubleshooting I/O fencing
- Node is unable to join cluster while another node is being ejected
- The vxfentsthdw utility fails when SCSI TEST UNIT READY command fails
- Manually removing existing keys from SCSI-3 disks
- System panics to prevent potential data corruption
- Cluster ID on the I/O fencing key of coordinator disk does not match the local cluster's ID
- Fencing startup reports preexisting split-brain
- Registered keys are lost on the coordinator disks
- Replacing defective disks when the cluster is offline
- The vxfenswap utility exits if rcp or scp commands are not functional
- 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 the steward process
- Troubleshooting licensing
- Validating license keys
- Licensing error messages
- [Licensing] Insufficient memory to perform operation
- [Licensing] No valid VCS license keys were found
- [Licensing] Unable to find a valid base VCS license key
- [Licensing] License key cannot be used on this OS platform
- [Licensing] VCS evaluation period has expired
- [Licensing] License key can not be used on this system
- [Licensing] Unable to initialize the licensing framework
- [Licensing] QuickStart is not supported in this release
- [Licensing] Your evaluation period for the feature has expired. This feature will not be enabled the next time VCS starts
- 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
How membership arbitration works
Upon startup of the cluster, all systems register a unique key on the coordinator disks. The key is unique to the cluster and the node, and is based on the LLT cluster ID and the LLT system ID.
See About the I/O fencing registration key format.
When there is a perceived change in membership, membership arbitration works as follows:
GAB marks the system as DOWN, excludes the system from the cluster membership, and delivers the membership change - the list of departed systems - to the fencing module.
The system with the lowest LLT system ID in the cluster races for control of the coordinator disks
In the most common case, where departed systems are truly down or faulted, this race has only one contestant.
In a split brain scenario, where two or more subclusters have formed, the race for the coordinator disks is performed by the system with the lowest LLT system ID of that subcluster. This system that races on behalf of all the other systems in its subcluster is called the RACER node and the other systems in the subcluster are called the SPECTATOR nodes.
During the I/O fencing race, if the RACER node panics or if it cannot reach the coordination points, then the VxFEN RACER node re-election feature allows an alternate node in the subcluster that has the next lowest node ID to take over as the RACER node.
The racer re-election works as follows:
In the event of an unexpected panic of the RACER node, the VxFEN driver initiates a racer re-election.
If the RACER node is unable to reach a majority of coordination points, then the VxFEN module sends a RELAY_RACE message to the other nodes in the subcluster. The VxFEN module then re-elects the next lowest node ID as the new RACER.
With successive re-elections if no more nodes are available to be re-elected as the RACER node, then all the nodes in the subcluster will panic.
The race consists of executing a preempt and abort command for each key of each system that appears to no longer be in the GAB membership.
The preempt and abort command allows only a registered system with a valid key to eject the key of another system. This ensures that even when multiple systems attempt to eject other, each race will have only one winner. The first system to issue a preempt and abort command will win and eject the key of the other system. When the second system issues a preempt and abort command, it cannot perform the key eject because it is no longer a registered system with a valid key.
If the value of the cluster-level attribute PreferredFencingPolicy is System, Group, or Site then at the time of a race, the VxFEN Racer node adds up the weights for all nodes in the local subcluster and in the leaving subcluster. If the leaving partition has a higher sum (of node weights) then the racer for this partition will delay the race for the coordination point. This effectively gives a preference to the more critical subcluster to win the race. If the value of the cluster-level attribute PreferredFencingPolicy is Disabled, then the delay will be calculated, based on the sums of node counts.
If the preempt and abort command returns success, that system has won the race for that coordinator disk.
Each system will repeat this race to all the coordinator disks. The race is won by, and control is attained by, the system that ejects the other system's registration keys from a majority of the coordinator disks.
On the system that wins the race, the vxfen module informs all the systems that it was racing on behalf of that it won the race, and that subcluster is still valid.
On the system(s) that do not win the race, the vxfen module will trigger a system panic. The other systems in this subcluster will note the panic, determine they lost control of the coordinator disks, and also panic and restart.
Upon restart, the systems will attempt to seed into the cluster.
If the systems that restart can exchange heartbeat with the number of cluster systems declared in /etc/gabtab, they will automatically seed and continue to join the cluster. Their keys will be replaced on the coordinator disks. This case will only happen if the original reason for the membership change has cleared during the restart.
If the systems that restart cannot exchange heartbeat with the number of cluster systems declared in /etc/gabtab, they will not automatically seed, and HAD will not start. This is a possible split brain condition, and requires administrative intervention.
If you have I/O fencing enabled in your cluster and if you have set the GAB auto-seeding feature through I/O fencing, GAB automatically seeds the cluster even when some cluster nodes are unavailable.
See Seeding a cluster using the GAB auto-seed parameter through I/O fencing.
Note:
Forcing a manual seed at this point will allow the cluster to seed. However, when the fencing module checks the GAB membership against the systems that have keys on the coordinator disks, a mismatch will occur. vxfen will detect a possible split brain condition, print a warning, and will not start. In turn, HAD will not start. Administrative intervention is required.