Storage Foundation for Oracle® RAC 7.4.1 Administrator's Guide - Linux

Evaluating VCS I/O fencing ports

I/O Fencing (VxFEN) uses a dedicated port that GAB provides for communication across nodes in the cluster. You can see this port as port 'b' when gabconfig -a runs on any node in the cluster. The entry corresponding to port 'b' in this membership indicates the existing members in the cluster as viewed by I/O Fencing.

GAB uses port "a" for maintaining the cluster membership and must be active for I/O Fencing to start.

To check whether fencing is enabled in a cluster, the '-d' option can be used with vxfenadm (1M) to display the I/O Fencing mode on each cluster node. Port "b" membership should be present in the output of gabconfig -a and the output should list all the nodes in the cluster.

If the GAB ports that are needed for I/O fencing are not up, that is, if port "a" is not visible in the output of gabconfig -a command, LLT and GAB must be started on the node.

The following commands can be used to start LLT and GAB respectively:

To start LLT on each node:

For RHEL 7, SLES 12, and supported RHEL distributions:

# systemctl start llt

For earlier versions of RHEL, SLES, and supported RHEL distributions:

# /etc/init.d/llt start

If LLT is configured correctly on each node, the console output displays:

LLT INFO V-14-1-10009 LLT Protocol available

To start GAB, on each node:

For RHEL 7, SLES 12, and supported RHEL distributions:

# systemctl start gab

For earlier versions of RHEL, SLES, and supported RHEL distributions:

# /etc/init.d/gab start

If GAB is configured correctly on each node, the console output displays:

GAB INFO V-15-1-20021 GAB available

GAB INFO V-15-1-20026 Port a registration waiting for seed port membership