SFHA Solutions 6.0.1: About GAB seeding and its role in VCS and other SFHA products
Group Membership and Atomic Broadcast (GAB) is a kernel component of Veritas Cluster Server (VCS) that provides globally-ordered messages that keep nodes synchronized. GAB maintains the cluster state information and the correct membership on the cluster. However, GAB needs another kernel component, Low Latency Transport (LLT), to send messages to the nodes and keep the cluster nodes connected. How GAB and LLT function together in a VCS cluster? VCS uses GAB and LLT to share data among nodes over private networks. LLT is the transport protocol responsible for fast kernel-to-kernel communications. GAB carries the state of the cluster and the cluster configuration to all the nodes on the cluster. These components provide the performance and reliability that VCS requires. In a cluster, nodes must share the groups, resources and the resource states. LLT and GAB help the nodes communicate. For information on LLT, GAB, and private networks, see: About LLT and GAB About network channels for heartbeating GAB seeding The GAB seeding function ensures that a new cluster starts with an accurate membership count of the number of nodes in the cluster. It prevents your cluster from a preexisting network partition upon initial start-up. A preexisting network partition refers to the failure in the communication channels that occurs while the nodes are down and VCS cannot respond. When the nodes start, GAB seeding reduces the vulnerability to network partitioning, regardless of the cause of the failure. GAB services are used by all Veritas Storage Foundation and High Availability (SFHA) products. For information about preexisting network partitions, and how seeding functions in VCS, see: About preexisting network partitions About VCS seeding Enabling automatic seeding of GAB If I/O fencing is configured in the enabled mode, you can edit the /etc/vxfenmode file to enable automatic seeding of GAB. If the cluster is stuck with a preexisting split-brain condition, I/O fencing allows automatic seeding of GAB. You can set the minimum number of nodes to form a cluster for GAB to seed by configuring the Control port seed and Quorum flag parameters in the /etc/gabtab file. Quorum is the number of nodes that need to join a cluster for GAB to complete seeding. For information on configuring the autoseed_gab_timeout parameter in the /etc/vxfenmode file, see: About I/O fencing configuration files For information on configuring the control port seed and the Quorum flag parameters in GAB, see: About GAB run-time or dynamic tunable parameters For information on split-brain conditions, see: About the Steward process: Split-brain in two-cluster global clusters How I/O fencing works in different event scenarios Example of a preexisting network partition (split-brain) Role of GAB seeding in cluster membership For information on how the nodes gain cluster membership, seeding a cluster, and manual seeding of a cluster, see: About cluster membership Initial joining of systems to cluster membership Seeding a new cluster Seeding a cluster using the GAB auto-seed parameter through I/O fencing Manual seeding of a cluster Troubleshooting issues that are related to GAB seeding and preexisting network partitions For information on the issues that you may encounter when GAB seeds a cluster and preexisting network partitions, see: Examining GAB seed membership Manual GAB membership seeding Waiting for cluster membership after VCS start-up Summary of best practices for cluster communications System panics to prevent potential data corruption Fencing startup reports preexisting split-brain Clearing preexisting split-brain condition Recovering from a preexisting network partition (split-brain) Example Scenario I – Recovering from a preexisting network partition Example Scenario II – Recovering from a preexisting network partition Example Scenario III – Recovering from a preexisting network partition gabconfig (1M) 6.0.1 manual pages: AIX Solaris For more information on seeding clusters to prevent preexisting network partitions, see: Veritas Cluster Server Administrator's Guide Veritas Cluster Server Installation Guide Veritas Cluster Server documentation for other releases and platforms can be found on the SORT website.SFHA Solutions 6.2: Symantec Storage plug-in for OEM 12c
Symantec Storage plug-in for OEM12c enables you to view and manage the Storage Foundation and VCS objects through the Oracle Enterprise Manager 12c (OEM), which has a graphical interface. It works with the Symantec Storage Foundation and High Availability 6.2 product suite. The Symantec Storage plug-in allows you to: SmartIO: manage Oracle database objects using SmartIO. Snapshot: create point-in-time copies (Storage Checkpoint, Database FlashSnap, Space-optimized Snapshot, and FileSnap) of Oracle databases using SFDB features Cluster: vew cluster-specific information. You can get the plug-in by downloading the attached file. For more information about installing and using the plug-in, download the attached Application Note. Terms of use for this information are found in Legal Notices.