These are the details :

/sbin/gabconfig -c -n2 command fails to configure GAB driver with error

 GAB /sbin/gabconfig ERROR V-15-2-25022 unknown error

The cause of the GAB driver configuration issue is inconsistency in system name in VCS configuration.

The inconsistent system name will result in some VCS engine (had) start up errors (contained in VCS engine_A.log) below.

2009/11/20 22:45:44 VCS ERROR V-16-1-10391 System 'server_A' listed in main.cf but absent in LLT config file
2009/11/20 22:45:44 VCS ERROR V-16-1-10068 System server_A - VCS engine will exit to prevent any inconsistency. Please review names of systems listed in VCS configuration and make sure they are present and node ids are consistent in LLT configuration files on all systems in the cluster

To fix the issue, follow the procedures below:

1. check and made sure that the GAB module is loaded.
 
2. check and make sure that the system name in /etc/VRTSvcs/conf/sysname and in main.cf and llthosts are same

3. run gabconfig -c -n2 command to configure GAB driver after performing the above two steps

4. run gabconfig -a to confirm that GAB port a membership is configured.

5. run hastart to start VCS