Shared disk tiebreaker

Set up a disk tiebreaker in a cluster that has an even number of nodes. The tie breaker disk is shared between all cluster nodes.

A disk can be used as tiebreaker resource by using the IBM.TieBreaker resource class. In case only half of the number of nodes are online in a sub-domain, System Automation for Multiplatforms tries to reserve the tiebreaker disk by using the reserve or release function. If the reserve is successful, the sub-domain gets the quorum, and System Automation for Multiplatforms might continue to automate resources. The reservation of the disk is released when another node joins the domain, so that more than half of the nodes are online in that domain.

Note: When you define the tiebreaker, make sure the disk that you specify for the IBM.TieBreaker resource is not also used to store file systems.

The following three examples show how to use a tiebreaker with an ECKD, SCSI or DISK device. The tiebreaker does not need to be formatted or partitioned.