A system administrator applies static settings to resources and resource groups. You can change these settings only by administrative action. The RGM moves resource groups between dynamic “states.”
These settings and states are as follows:
Managed or unmanaged settings. These cluster-wide settings apply only to resource groups. The RGM manages resource groups. You can use the clresourcegroup command to request that the RGM manage or unmanage a resource group. These resource group settings do not change when you reconfigure a cluster.
When a resource group is first created, it is unmanaged. A resource group must be managed before any resources placed in the group can become active.
In some data services, for example, a scalable web server, work must be done prior to starting network resources and after they are stopped. This work is done by initialization (INIT) and finish (FINI) data service methods. The INIT methods only run if the resource group in which the resources are located is in the managed state.
When a resource group is moved from unmanaged to managed, any registered INIT methods for the group are run on the resources in the group.
When a resource group is moved from managed to unmanaged, any registered FINI methods are called to perform cleanup.
The most common use of the INIT and FINI methods are for network resources for scalable services. However, a data service developer can use these methods for any initialization or cleanup work that is not performed by the application.
Enabled or disabled settings. These settings apply to resources on one or more nodes. A system administrator can use the clresource command to enable or disable a resource on one or more nodes. These settings do not change when the cluster administrator reconfigures a cluster.
The normal setting for a resource is that it is enabled and actively running in the system.
If you want to make the resource unavailable on all cluster nodes, disable the resource on all cluster nodes. A disabled resource is not available for general use on the cluster nodes that you specify.
Online or offline states. These dynamic states apply to both resources and resource groups.
Online and offline states change as the cluster transitions through cluster reconfiguration steps during switchover or failover. You can also change the online or offline state of a resource or a resource group by using the clresource and clresourcegroup commands.
A failover resource or resource group can only be online on one node at any time. A scalable resource or resource group can be online on some nodes and offline on others. During a switchover or failover, resource groups and the resources within them are taken offline on one node and then brought online on another node.
If a resource group is offline, all of its resources are offline. If a resource group is online, all of its enabled resources are online.
You can temporarily suspend the automatic recovery actions of a resource group. You might need to suspend the automatic recovery of a resource group to investigate and fix a problem in the cluster. Or, you might need to perform maintenance on resource group services.
A suspended resource group is not automatically restarted or failed over until you explicitly issue the command that resumes automatic recovery. Whether online or offline, suspended data services remain in their current state. You can still manually switch the resource group to a different state on specified nodes. You can also still enable or disable individual resources in the resource group.
Resource groups can contain several resources, with dependencies between resources. These dependencies require that the resources be brought online and offline in a particular order. The methods that are used to bring resources online and offline might take different amounts of time for each resource. Because of resource dependencies and start and stop time differences, resources within a single resource group can have different online and offline states during a cluster reconfiguration.