The Resource Group Manager (RGM) is implemented as a daemon, rgmd, that runs in the global zone on each member node of a cluster. All of the rgmd processes communicate with each other and act as a single cluster-wide facility.
The RGM supports the following functions:
Whenever a node or zone boots or crashes, the RGM attempts to maintain the availability of all managed resource groups. The RGM does so by automatically bringing them online on correct masters.
If a particular resource fails, its monitor program can request that the resource group be restarted on the same master or switched to a new master.
The cluster administrator can issue an administrative command to request one of the following actions:
Change mastery of a resource group.
Enable or disable a particular resource within a resource group.
Create, delete, or modify a resource type, a resource, or a resource group.
Whenever the RGM activates configuration changes, it coordinates its actions across all member nodes of the cluster. This kind of activity is known as a reconfiguration. To effect a state change on an individual resource, the RGM runs a resource type-specific callback method on that resource.