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Measures reported by ClusterResTest
A resource is a physical or logical entity that is capable of being managed by a cluster, brought online, taken offline, and moved between nodes. A resource can be owned only by a single node at any point in time.
This test reports the number of resources in the cluster and their current states.
| Measurement |
Description |
Measurement
Unit |
Interpretation |
| Resource_online |
Indicates the number of resources that are currently online. |
Number |
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| Resource_offline |
Indicates the number of resources that are currently offline. |
Number |
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| Resource_failed |
Indicates the number of resources that have failed |
Number |
Typically, a resource failure triggers a recovery action, which could be a resource restart or a transfer of the resource to another node.
Typically, the Failover Manager and Resource Monitor work together to detect and recover from resource failures. Resource Monitors keep track of resource status by using the resource DLLs to periodically poll resources. Polling involves two steps, a cursory LooksAlive query and a longer, more definitive, IsAlive query. When Resource Monitor detects a resource failure, it notifies Failover Manager and continues to monitor the resource.
Failover Manager maintains resources and resource group status. It also performs recovery when a resource fails and invokes Resource Monitors in response to user actions or failures.
After a resource failure is detected, Failover Manager performs recovery actions that include restarting a resource and its dependent resources, or moving the entire resource group to another node. The recovery action that is taken is determined by resource and resource group properties, in addition to node availability.
During failover, the resource group is treated as the unit of failover. This ensures that resource dependencies are correctly recovered. When a resource recovers from a failure, Resource Monitor notifies Failover Manager. Failover Manager then performs automatic failback of the resource group, based on the configuration of the resource group failback properties.
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