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
About LLT timer tunable parameters
Table: LLT timer tunable parameters lists the LLT timer tunable parameters. The timer values are set in .01 sec units. The command lltconfig - T query can be used to display current timer values.
Table: LLT timer tunable parameters
LLT parameter | Description | Default | When to change | Dependency with other LLT tunable parameters |
---|---|---|---|---|
peerinact | LLT marks a link of a peer node as "inactive," if it does not receive any packet on that link for this timer interval. Once a link is marked as "inactive," LLT will not send any data on that link. | 1600 |
| The timer value should always be higher than the peertrouble timer value. |
rpeerinact | Mark RDMA channel of a RDMA link as "inactive", if the node does not receive any packet on that link for this timer interval. Once RDMA channel is marked as "inactive", LLT does not send any data on the RDMA channel of that link, however, it may continue to send data over non-RDMA channel of that link until peerinact expires. You can view the status of the RDMA channel of a RDMA link using lltstat -nvv -r command. This parameter is supported only on selected versions of Linux. | 700 | Decrease the value of this tunable for speeding up the RDMA link failure recovery. If the links are unstable, and they are going up and down frequently then do not decrease this value. | This timer value should always be greater than peertrouble timer value and less than peerinact value. |
peertrouble | LLT marks a high-pri link of a peer node as "troubled", if it does not receive any packet on that link for this timer interval. Once a link is marked as "troubled", LLT will not send any data on that link till the link is up. | 200 |
| This timer value should always be lower than peerinact timer value. Also, It should be close to its default value. |
peertroublelo | LLT marks a low-pri link of a peer node as "troubled", if it does not receive any packet on that link for this timer interval. Once a link is marked as "troubled", LLT will not send any data on that link till the link is available. | 400 |
| This timer value should always be lower than peerinact timer value. Also, It should be close to its default value. |
heartbeat | LLT sends heartbeat packets repeatedly to peer nodes after every heartbeat timer interval on each highpri link. | 50 | In some circumstances, when the private networks links are very slow (or congested) or nodes in the cluster are very busy, increase the value. | This timer value should be lower than peertrouble timer value. Also, it should not be close to peertrouble timer value. |
heartbeatlo | LLT sends heartbeat packets repeatedly to peer nodes after every heartbeatlo timer interval on each low pri link. | 100 | In some circumstances, when the networks links are very slow or nodes in the cluster are very busy, increase the value. | This timer value should be lower than peertroublelo timer value. Also, it should not be close to peertroublelo timer value. |
timetoreqhb | If LLT does not receive any packet from the peer node on a particular link for "timetoreqhb" time period, it attempts to request heartbeats (sends 5 special heartbeat requests (hbreqs) to the peer node on the same link) from the peer node. If the peer node does not respond to the special heartbeat requests, LLT marks the link as "expired" for that peer node. The value can be set from the range of 0 to (peerinact -200). The value 0 disables the request heartbeat mechanism. | 1400 | Decrease the value of this tunable for speeding up node/link inactive notification mechanism as per client's notification processing logic. Disable the request heartbeat mechanism by setting the value of this timer to 0 for planned replacement of faulty network cable /switch. In some circumstances, when the private networks links are very slow or the network traffic becomes very bursty, don't change the value of this timer tunable. | This timer is set to 'peerinact - 200' automatically every time when the peerinact timer is changed. |
reqhbtime | This value specifies the time interval between two successive special heartbeat requests. See the timetoreqhb parameter for more information on special heartbeat requests. | 40 | Veritas recommends that you do not change this value. | Not applicable |
timetosendhb | LLT sends out of timer context heartbeats to keep the node alive when LLT timer does not run at regular interval. This option specifies the amount of time to wait before sending a heartbeat in case of timer not running. If this timer tunable is set to 0, the out of timer context heartbeating mechanism is disabled. | 200 | Disable the out of timer context heart-beating mechanism by setting the value of this timer to 0 for planned replacement of faulty network cable /switch. In some circumstances, when the private networks links are very slow or nodes in the cluster are very busy, increase the value | This timer value should not be more than peerinact timer value. Also, it should not be close to the peerinact timer value. |
sendhbcap | This value specifies the maximum time for which LLT will send contiguous out of timer context heartbeats. | 18000 | Veritas recommends that you do not change this value. | NA |
oos | If the out-of-sequence timer has expired for a node, LLT sends an appropriate NAK to that node. LLT does not send a NAK as soon as it receives an oos packet. It waits for the oos timer value before sending the NAK. | 10 | Do not change this value for performance reasons. Lowering the value can result in unnecessary retransmissions/negative acknowledgement traffic. You can increase the value of oos if the round trip time is large in the cluster (for example, campus cluster). | Not applicable |
retrans | LLT retransmits a packet if it does not receive its acknowledgement for this timer interval value. | 10 | Do not change this value. Lowering the value can result in unnecessary retransmissions. You can increase the value of retrans if the round trip time is large in the cluster (for example, campus cluster). | Not applicable |
service | LLT calls its service routine (which delivers messages to LLT clients) after every service timer interval. | 100 | Do not change this value for performance reasons. | Not applicable |
arp | LLT flushes stored address of peer nodes when this timer expires and relearns the addresses. | 0 | This feature is disabled by default. | Not applicable |
arpreq | LLT sends an arp request when this timer expires to detect other peer nodes in the cluster. | 3000 | Do not change this value for performance reasons. | Not applicable |