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
VCS behavior on loss of storage connectivity
When a node loses connectivity to shared storage, input-output operations (I/O) to volumes return errors and the disk group gets disabled. In this situation, VCS must fail the service groups over to another node. This failover is to ensure that applications have access to shared storage. The failover involves deporting disk groups from one node and importing them to another node. However, pending I/Os must complete before the disabled disk group can be deported.
Pending I/Os cannot complete without storage connectivity. When VCS is not configured with I/O fencing and the PanicSystemOnDGLoss attribute of DiskGroup is not configured to panic the system, VCS assumes data is being read from or written to disks and does not declare the DiskGroup resource as offline. This behavior prevents potential data corruption that may be caused by the disk group being imported on two hosts. However, this also means that service groups remain online on a node that does not have storage connectivity and the service groups cannot be failed over unless an administrator intervenes. This affects application availability.
Some Fibre Channel (FC) drivers have a configurable parameter called failover, which defines the number of seconds for which the driver retries I/O commands before returning an error. If you set the failover parameter to 0, the FC driver retries I/O infinitely and does not return an error even when storage connectivity is lost. This also causes the Monitor function for the DiskGroup to time out and prevents failover of the service group unless an administrator intervenes.