Veritas Storage Foundation 5.1 SP1 for Oracle RAC Administrator"s Guide (5900-1512, April 2011)

See “How vxfen driver checks for preexisting split-brain condition” on page 203.

How vxfen driver checks for preexisting split-brain condition

The vxfen driver functions to prevent an ejected node from rejoining the cluster

after the failure of the private network links and before the private network links

are repaired.

For example, suppose the cluster of system 1 and system 2 is functioning normally

when the private network links are broken. Also suppose system 1 is the ejected

system. When system 1 restarts before the private network links are restored, its

membership configuration does not show system 2; however, when it attempts

to register with the coordinator disks, it discovers system 2 is registered with

them. Given this conflicting information about system 2, system 1 does not join

the cluster and returns an error from vxfenconfig that resembles:

vxfenconfig: ERROR: There exists the potential for a preexisting

split-brain. The coordinator disks list no nodes which are in

the current membership. However, they also list nodes which are

not in the current membership.

I/O Fencing Disabled!

Note: During the system boot, because the HP-UX rc sequencer redirects the stderr

of all rc scripts to the file /etc/rc.log, the error messages will not be printed on

the console. It will be logged in the /etc/rc.log file.

Also, the following information is displayed on the console:

<date> <system name> vxfen: WARNING: Potentially a preexisting

<date> <system name> split-brain.

<date> <system name> Dropping out of cluster.

<date> <system name> Refer to user documentation for steps

<date> <system name> required to clear preexisting split-brain.

<date> <system name> I/O Fencing DISABLED!

<date> <system name> gab: GAB:20032: Port b closed

Note: If syslogd is configured with the -D option, then the informational message

will not be printed on the console. The messages will be logged in the system

buffer. The system buffer can be read with the dmesg command.

203Troubleshooting SF Oracle RAC

Troubleshooting I/O fencing