As part of the start effort evaluation, the first decision that Oracle Clusterware must make is where to start (or place) the resource. Making such a decision is easy when the caller specifies the target server by name. If a target server is not specified, however, then Oracle Clusterware attempts to locate the best possible server for placement given the resource's configuration and the current state of the cluster.
Oracle Clusterware considers a resource's placement policy first and filters out servers that do not fit with that policy. Oracle Clusterware sorts the remaining servers in a particular order depending on the value of the PLACEMENT resource attribute of the resource.
See Also:
"Application Placement Policies" for more information about the PLACEMENT resource attribute
The result of this consideration is a maximum of two lists of candidate servers on which Oracle Clusterware can start the resource. One list contains preferred servers and the other contains possible servers. The list of preferred servers will be empty if the value of the PLACEMENT resource attribute for the resource is set to balanced or restricted. The placement policy of the resource determines on which server the resource wants to run. Oracle Clusterware considers preferred servers over possible servers, if there are servers in the preferred list.
Oracle Clusterware then considers the resource's dependencies to determine where to place the resource, if any exist. The attraction and dispersion start dependencies affect the resource placement decision, as do some dependency modifiers. Oracle Clusterware applies these placement hints to further order the servers in the two previously mentioned lists. Note that Oracle Clusterware processes each list of servers independently, so that the effect of the resource's placement policy is not confused by that of dependencies.
Finally, Oracle Clusterware chooses the first server from the list of preferred servers, if any servers are listed. If there are no servers on the list of preferred servers, then Oracle Clusterware chooses the first server from the list of possible servers, if any servers are listed. When no servers exist in either list, Oracle Clusterware generates a resource placement error.
Note:
Neither the placement policies nor the dependencies of the resources related to the resource Oracle Clusterware is attempting to start affect the placement decision.