Managing DRS Clusters

The vSphere Client UI allows you to explore DRS cluster behavior, which is also described in the Resource Management Guide. When DRS is running, it generates recommendations and associated information that result in a well balanced cluster.

■	Initial placement of virtual machines

■	Virtual machine migration for load balancing. Each migration recommendation has a rating, which you can find in the ClusterRecommendation.rating property. Client applications can choose to consider only high-priority migrations are considered or migrations with multiple priority levels.

■	Checks whether DRS clusters are valid — enough resources are available to start additional virtual machines — or not valid.

DRS recommentations are stored in the ClusterComputeResource.recommendation property, which is an array of ClusterRecommendation data objects. Each ClusterRecommendation includes information about the action to perform and information you can use to display information to end users or for logging.

■	Client applications can call ClusterComputeResource.ApplyRecommendation to apply one or more recommendations.

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For more fine-grained control, client applications can perform individual actions only. The ClusterRecommendation.action property is an array of ClusterAction objects. Each ClusterAction includes a target for the action and the type, which is a string that is one of the values of the ActionType enum (HostPowerV1, MigrationV1, VmPowerV1). Client applications can use the ActionType information to act on DRS recommendations by powering on hosts, migrating virtual machines, or powering on virtual machines by calling Datacenter.PowerOnMultiVM_Task.