# Troubleshooting high availability issues
Troubleshooting high availability issues

You can find information following about actions to take if you experience availability issues.

**Topics**
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## Health notifications
](#ha-health-notifications)
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## Metrics
](#ha-health-notification-metrics)

## Health notifications
Health notifications

When you run your gateway on VMware vSphere HA, all gateways produce the following health notifications to your configured Amazon CloudWatch log group. These notifications go into a log stream called `AvailabilityMonitor`.

**Topics**
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### Notification: Reboot
](#troubleshoot-reboot-notification)
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### Notification: HardReboot
](#troubleshoot-hardreboot-notification)
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### Notification: HealthCheckFailure
](#troubleshoot-healthcheckfailure-notification)
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### Notification: AvailabilityMonitorTest
](#troubleshoot-availabilitymonitortest-notification)

### Notification: Reboot
Notification: Reboot

You can get a reboot notification when the gateway VM is restarted. You can restart a gateway VM by using the VM Hypervisor Management console or the Storage Gateway console. You can also restart by using the gateway software during the gateway's maintenance cycle.

**Action to Take**

If the time of the reboot is within 10 minutes of the gateway's configured [maintenance start time](MaintenanceManagingUpdate-common.md), this is probably a normal occurrence and not a sign of any problem. If the reboot occurred significantly outside the maintenance window, check whether the gateway was restarted manually.

### Notification: HardReboot
Notification: HardReboot

You can get a `HardReboot` notification when the gateway VM is restarted unexpectedly. Such a restart can be due to loss of power, a hardware failure, or another event. For VMware gateways, a reset by vSphere High Availability Application Monitoring can launch this event.

**Action to Take**

When your gateway runs in such an environment, check for the presence of the `HealthCheckFailure` notification and consult the VMware events log for the VM.

### Notification: HealthCheckFailure
Notification: HealthCheckFailure

For a gateway on VMware vSphere HA, you can get a `HealthCheckFailure` notification when a health check fails and a VM restart is requested. This event also occurs during a test to monitor availability, indicated by an `AvailabilityMonitorTest` notification. In this case, the `HealthCheckFailure` notification is expected.

**Note**  
This notification is for VMware gateways only.

**Action to Take**

If this event repeatedly occurs without an `AvailabilityMonitorTest` notification, check your VM infrastructure for issues (storage, memory, and so on). If you need additional assistance, contact Support. 

### Notification: AvailabilityMonitorTest
Notification: AvailabilityMonitorTest

For a gateway on VMware vSphere HA, you can get an `AvailabilityMonitorTest` notification when you [run a test](vmware-ha.md#vmware-ha-test-failover) of the [Availability and application monitoring](https://docs.aws.amazon.com/storagegateway/latest/APIReference/API_StartAvailabilityMonitorTest.html) system in VMware.

## Metrics
Metrics

The `AvailabilityNotifications` metric is available on all gateways. This metric is a count of the number of availability-related health notifications generated by the gateway. Use the `Sum` statistic to observe whether the gateway is experiencing any availability-related events. Consult with your configured CloudWatch log group for details about the events.