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
Stale key detection to avoid a false preexisting split brain condition
When a cluster starts, all the cluster nodes register their unique keys on the coordination point servers (CP servers). The key is unique to the cluster and the node, and is based on the LLT cluster ID and the LLT node ID. When the network connectivity between the cluster nodes and the CP servers is lost, as the nodes go offline, some stale keys may be left on one or more CP servers. The presence of a key on a CP server indicates that the corresponding node is alive. Thus, after the network connectivity is restored, the presence of a stale key of a node that freshly comes online creates a false preexisting split brain in the cluster. When a false preexisting split brain is detected, the node fails to start, and manual intervention is required to bring the cluster online.
Cluster Server provides a reliable method to identify a false preexisting split brain condition that is caused by the presence of such stale keys. The CP server functionality detects such stale keys and provide this information to the vxfen
module. The vxfen
module performs its arbitration and brings the cluster online.
This feature is available only on Linux when the following criteria are met:
vxfen_mode is set to customized.
Majority of the coordination points are servers.
detect_false_pesb attribute is set to 1.
To enable stale key detection in a server-based fencing configuration
- Stop VCS on all nodes.
# hastop -all
- Make sure that the port h is closed on all the nodes. Run the following command on each node to verify that the port h is closed:
# gabconfig -a
Port h must not appear in the output.
- Stop I/O fencing on all nodes. Run the following command on each node:
# /etc/init.d/vxfen stop
- If you have any applications that run outside of VCS control that have access to the shared storage, shut down all the other nodes in the cluster that have access to the shared storage. This prevents data corruption.
- Open the
/etc/vxfenmode
file, add detect_false_pesb=1 at the appropriate location, and save and close the file. - Start the fencing module on all the nodes.
# /etc/init.d/vxfen start
- Start VCS on all nodes.
# hastart