Compaq AA-Q88CE-TE manual SET Partition test/PRIORITYLIST=bronze,gold

Starting and Setting Up RTR

2.12 How RTR Selects Processing-states (Roles) for Nodes

8.The network connection to node Gold is reestablished. The partition on Gold retained its original sequence number of 2 and retains the primary role while the partition on Bronze reassumes the secondary role.

Alternately, the roles of backend nodes can be specifically assigned with the /PRIORITY_LIST qualifier to the SET PARTITION command. In the previous example the /PRIORITY_LIST qualifier can be used to insure that when Bronze fails and then returns to participate in the facility it then becomes the active primary member. To insure this, the following command would be issued on both backend systems immediately after the creation of the partition:

SET PARTITION test/PRIORITY_LIST=(bronze,gold)

It is recommended that the same priority list order be used on all partition members. If a different list is used then the router will determine the sequence number for conflicting members through the order in which those members joined the facility. For example, if the above command were issued only on Bronze and Gold had the opposite priority list, then the router would assign the lower sequence number to the backend that joined the facility first.

The /PRIORITY_LIST feature is very useful in cluster configurations. For example, Site A and Site B each contain 2-node clusters. The facility is configured such that at Site A, Node-A1 has the primary active partition and Node-A2 has the standby partition. At Site B, Node-B1 is the secondary active partition and Node-B2 has the standby of the secondary. The partition could be defined such that the standby node, Node-A2, would become active if the primary node were to fail. For example, issuing the following command on all four nodes for this partition guarantees that the specified list is followed when there is a failure.

SET PARTITION test/PRIORITY_LIST=(Node-A1,Node-A2,Node-B1,Node-B2)

Using the SHOW PARTITION command from the router, this partition would be as follows:

Router partitions on node SILVER in group "test" at Mon Mar 22 17:22:06 1999

State:	ACTIVE
Low bound:	0	High bound:	4294967295
Failover policy:			fail_to_standby
Backends:		node-a1,node-a2,node-b1,node-b2
States:		pri_act,standby,sec_act,standby
Relative priorities:			1,2,3,4
Primary main:	node-a1	Shadow main:	node-b1

However, the partition could also be configured so that the secondary active node, Node-B1, would become the primary node if the original primary system were to fail. This is controlled with the /FAILOVER_POLICY qualifier to the SET PARTITION command. The default is /FAILOVER_POLICY=STAND_BY.

2–20Starting and Setting Up RTR