A maintenance mode for hosts is implemented in ADCM. This mode is designed to stop the implementation of any cluster- or service-related operations for a host. You also can’t add any components to the host that is in maintenance mode. This is useful if the host is turned off, has malfunctioned, or is not ready to participate in ADCM actions for some reason.
Consider using maintenance mode when you perform hardware or software maintenance, change configuration settings, perform troubleshooting, decommissioning, or removing cluster nodes.
Not every cluster, service, or component action is possible if one of cluster hosts is in maintenance mode. This depends on if the action affects all cluster hosts, as well as on action’s logic.
To switch a host to maintenance mode, you should perform the following steps:
- Locate the host you wish to switch to maintenace mode in ADCM interface. For instance, you can use the Hosts subsection of the Clusters tab.
- Click the maintenance mode icon. The icon turns red. The host is now in maintenance mode.
- To switch off the maintenace mode, click the maintenance mode icon again.
While you can’t perform any operations with components on a host that is in maintenance mode, you can still remove a component from this host on the logical level. Generally speaking, the maintenance mode prevents bulk operations being performed on a host, yet you may explicitly start and stop a component on a host while in maintenance mode.