The Resource Group Manager (RGM) is implemented as a daemon, rgmd, that runs on each global-cluster node. 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 fails, 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.