A resource can be started on any server, subject to the placement policies, the resource start dependencies, and the availability of the action script on that server.
PLACEMENT resource attribute determines how Oracle Clusterware selects a server on which to start a resource and where to relocate the resource after a server failure. The
SERVER_POOLS attributes determine eligible servers to host a resource and the
PLACEMENT attribute further refines the placement of resources.
Oracle Clusterware Resource Reference for more information about the
SERVER_POOLS resource attributes
The value of the
PLACEMENT resource attribute determines how Oracle Clusterware places resources when they are added to the cluster or when a server fails. Together with either the
SERVER_POOLS attributes, you can configure how Oracle Clusterware places the resources in a cluster. When the value of the
PLACEMENT attribute is:
balanced: Oracle Clusterware uses any online server pool for placement. Less loaded servers are preferred to servers with greater loads. To measure how loaded a server is, Oracle Clusterware uses the
LOAD resource attribute of the resources that are in an
ONLINE state on the server. Oracle Clusterware uses the sum total of the
LOAD values to measure the current server load.
favored: If a value is assigned to either of the
SERVER_CATEGORY resource attributes, then that value expresses a preference. If
HOSTING_MEMBERS is populated and either
SERVER_CATEGORY is set, then
HOSTING_MEMBERS indicates placement preference and
SERVER_CATEGORY indicates a restriction. For example, the
ora.cluster.vip resource has a policy that sets the value of
SERVER_CATEGORY is set to
HOSTING_MEMBERS is set to
server_name1. In this case, Oracle Clusterware restricts the placement of
ora.cluster.vip to the servers in the Hub category and then it prefers the server known as
restricted: Oracle Clusterware only considers servers that belong to server pools listed in the
SEVER_POOLS resource attribute, servers of a particular category as configured in the
SERVER_CATEGORY resource attribute, or servers listed in the
HOSTING_MEMBERS resource attribute for resource placement. Only one of these resource attributes can have a value, otherwise it results in an error.