Setting the active tiebreaker

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The OpQuorumTieBreaker persistent class attribute of the IBM.PeerNode class indicates the active tiebreaker for the peer domain.

A peer domain can have a number of tiebreakers (IBM.TieBreaker resources) defined, but only one can be active at a time. If there are multiple subdomains with the same number of nodes, the configuration resource manager uses this active tiebreaker after domain partitioning to determine which subdomain has operational quorum. Apart from the predefined tiebreaker resources, you can also define your own. Table 1 describes the predefined tiebreakers: operator, fail, and success.

Table 1. Predefined tiebreakers (**IBM.TieBreaker** resources)
Tiebreaker	Description
Operator	The system administrator resolves the tie by starting the ResolveOpQuorumTie action of the IBM.PeerDomain resource class. Until the administrator explicitly breaks the tie, neither domain has operational quorum. The OpQuorumState dynamic attribute of the PeerDomain resource is 1 (PendingQuorum) until the administer starts the ResolveOpQuorumTie action.
Fail	A pseudo tiebreaker in that it does not resolve the tie situation. Neither subdomain has operational quorum. The OpQuorumState dynamic attribute of each PeerDomain resource is 2 (NoQuorum). If critical resources are active on a domain that lost quorum (as indicated by the CritRsrcActive dynamic attribute of the PeerDomain resource), the configuration resource manager uses a critical resource protection method on the node to ensure that critical resources are not corrupted as a result of the domain partitioning.
Success	A pseudo tiebreaker that is always successful in resolving a tie so that each of the subdomain has operational quorum. The OpQuorumState dynamic attribute of each PeerDomain resource is 0 (HasQuorum). Therefore, if critical resources are active on a domain, they are not protected.

To view or set the active tiebreaker (OpQuorumTieBreaker persistent class attribute of the IBM.PeerNode class), use the standard RMC management commands: lsrsrc and chrsrc.

For example, to list the current active tiebreaker, use the lsrsrc command with its -c flag.

# lsrsrc -c IBM.PeerNode OpQuorumTieBreaker
Resource Class Persistent and Dynamic Attributes for: IBM.PeerNode
resource 1:
        OpQuorumTieBreaker = "Fail"

The preceding output shows that the current active tiebreaker is Fail. To list the names of all of the available tiebreaker resources, specify Name as a parameter on the lsrsrc command.

# lsrsrc IBM.TieBreaker Name
Resource Persistent and Dynamic Attributes for: IBM.TieBreaker
resource 1:
        Name = "Operator"
resource 2:
        Name = "Fail"
resource 3:
        Name = "Success"

To make the operator tiebreaker the active tiebreaker, use the chrsrc command with its -c flag.

CT_MANAGEMENT_SCOPE=2 chrsrc -c IBM.PeerNode OpQuorumTieBreaker="Operator"

If you set the active tiebreaker to Operator, and a tie situation occur, you need to manually resolve the tie by starting the ResolveOpQuorumTie action of the IBM.PeerDomain resource class.

For complete syntax information about the lsrsrc and chrsrc commands, see their man pages in Technical Reference: RSCT for AIX and Technical Reference: RSCT for Multiplatforms guides.