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title: Impaired Worker Monitoring
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locale: en-us
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source_site: docs.mulesoft.com
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---
product: CloudHub
---

# Impaired Worker Monitoring

> For the full documentation index, see: https://docs.mulesoft.com/llms.txt

CloudHub continuously verifies the health of the workers running Mule applications.

When a worker is impaired by hardware or software failures, including network unavailability, memory
issues, server hardware failures, or file corruption, CloudHub automatically attempts to restart the
app on a new worker.

Because CloudHub replaces impaired workers on a fixed schedule, which depends on the underlying
infrastructure, you might experience a delay between the time the new worker starts and when it
starts sharing the load. As long as the app is running on multiple workers, this delay shouldn’t
impact the application.

After the app is completely up and running, CloudHub switches the traffic to the new app instance
and deletes the old app instance, ensuring zero downtime.

If the application fails to start after five attempts, its status is **Failed** or **Unrecoverable
Runtime Error** and you must manually restart the application.

You see a notification indicating that the automatic restart occurred. The application log indicates
when an app is restarted automatically and any failures. For example:

```console
Your application was running on an impaired worker instance. To avoid any downtime, the platform has restarted the application.
```

> [!NOTE] The automatic worker-restart functionality is different from the automatic
> application-restart functionality, which is configurable using the **Automatically restart
> application when not responding** option on the **Settings** page for the app. CloudHub
> automatically attempts to restart impaired workers, regardless of the application-restart setting.

## Scheduled Maintenance Activities

CloudHub checks for these scheduled maintenance activities on the worker infrastructure that can
cause potential downtime for the running applications: reboot, stop, start, or replacement of the
instances. To ensure zero downtime, CloudHub schedules the app to restart automatically on a new
worker before the maintenance occurs.

You can restart your apps manually at your convenience or let CloudHub restart the app
automatically.

One month before the scheduled restart, the notification (bell) icon in the top right of both the
**Applications** page and the **Settings** page for the application turns red to indicate that you
have a new notification:

![Notification icon on the \*Settings\* page for the application](/mulesoft/current/en-us/cloudhub/_images/cloudhub-notification-icon.png)

Figure 1. The arrow shows the notification icon on the **Settings** page for the application.

Click the icon to display the notification, which includes the date that CloudHub will automatically
restart the worker.

CloudHub displays a reminder notification one week before automatic application restart.

## See Also

- [Notifications on Runtime Manager](https://docs.mulesoft.com/cloudhub/notifications-on-runtime-manager)

- [Application Monitoring and Automatic Restarts](https://docs.mulesoft.com/cloudhub/worker-monitoring)

- [Manage Deployed Applications](https://docs.mulesoft.com/runtime-manager/managing-deployed-applications)