In a situation when i encounter a split brain what should i do first is to shutdown the minicluster with the lower number of nodes or a node (if there are 2 node vcs) and then inform the manager or first inform the manager?
w_online shows me that i have a split brain.
Have you noticed all the Related posts on the right-hand side of the screen?
Have you had a look at them?
Other useful documentation is VCS Admin Guide.
Look for these topics:
About data protection
(Continue to read about I/O fencing)
About cluster membership and data protection without I/O fencing
Split brain should be prevented at all cost.
Above information and Related articles on the right will tell you how.
By the time you 'notice' a split brain situation, it is probably too late to take action.
Except contacting the Backup admin to restore corrupt data....