Maintenance Mode
Maintenance mode allows you to suppress alerts for a host, service, role, or even the entire cluster. This can be useful when you need to take actions in your cluster (make configuration changes and restart various elements) and do not want/need to see the alerts that will be generated due to those actions.
Putting a component into maintenance mode does not prevent events from being logged; it only suppresses the alerts that those events would otherwise generate. As a result, you can still see a history of the events that were recorded due to your actions.
You can enable maintenance mode for a service, a role, a host, or the entire cluster.
You can view the status of Maintenance Mode in your cluster with the View Maintenance Mode Status button from the All Services page. This button appears for each cluster, and separately for the Cloudera Management Services.
When you enter maintenance mode on a component (cluster, service, or host) that has subordinate components (for example, the roles for a service) the subordinate components are also put into maintenance mode. These are considered to be in "effective" maintenance mode, as they have inherited the setting from the higher-level component.
For example:
- If you set the HBase service into maintenance mode, then its roles (HBase Master and all Region Servers) are put into effective maintenance mode.
- If you set a host into maintenance mode, then any roles running on that host are put into effective maintenance mode.
Components that have been explicitly put into maintenance mode show the
following icon ( ). Components that have entered
effective maintenance mode as a result of inheritance from a higher-level component show
a similar icon, but it is gray and yellow instead of black and red (
).
Enabling Maintenance Mode
To put the entire cluster into maintenance mode:
- Go to the main Services page (All Services)
- From the Actions menu, select Enter Maintenance Mode.
- Confirm that you want to do this.
The cluster is put into explicit maintenance mode, as indicated by the black maintenance mode icon. All services and roles in the cluster are entered into effective maintenance mode, as indicated by the grey/yellow maintenance mode icon.
To put a service into maintenance mode:
- From the Actions menu for the individual service Enter Maintenance Mode.
- Confirm that you want to do this.
The service is put into explicit maintenance mode, as indicated by the black maintenance mode icon. All roles for the service are entered into effective maintenance mode, as indicated by the grey/yellow maintenance mode icon.
To put one or more individual roles into maintenance mode:
- Go to the Services page that includes the role.
- Go to the Instances tab.
- Select the role(s) you want to put into maintenance mode.
- From the Actions for Selected menu, select Enter Maintenance Mode.
- Confirm that you want to do this.
The role will be put in explicit maintenance mode.
If this role instance was already in effective maintenance mode (because its service or host was put into maintenance mode) the role will now be in effective maintenance mode. This means that it will NOT exit maintenance mode automatically if its host or service exits maintenance mode. It will need to be removed from maintenance mode explicitly.
To put one or more hosts into maintenance mode:
- Go to the Hosts page.
- Select the host(s) you want to put into maintenance mode.
- From the Actions for Selected menu, select Enter Maintenance Mode.
- Confirm that you want to do this.
The confirmation pop-up lists the role instances that will be put into effective maintenance mode when the host goes into maintenance mode.
Interaction between Explicit and Effective Maintenance Mode
When a component (role, host or service) is in effective maintenance mode, it can only be removed from maintenance mode when the higher-level component exits maintenance mode. For example, if you put a service into maintenance mode, then the roles associated with that service will be entered into effective maintenance mode, and will remain in effective maintenance mode until the service exits maintenance mode. You cannot remove them from maintenance mode individually.
On the other hand, a component that is in effective maintenance mode can be put into explicit maintenance mode – just select the individual component and use the Enter Maintenance Mode command. In this case, the component will remain in maintenance mode even when the higher-level component exits maintenance mode.
For example, suppose you put a host into maintenance mode, (which puts all the roles on that host into effective maintenance mode). You then select one of the roles on that host and put it explicitly into maintenance mode. When you have the host exit maintenance mode, that one role will remain in maintenance mode. You will need to select it individually and specifically have it exit maintenance mode.
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