# Troubleshooting high availability issues
<a name="troubleshooting-ha-issues"></a>

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

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

## Health notifications
<a name="ha-health-notifications"></a>

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

### Notification: Reboot
<a name="troubleshoot-reboot-notification"></a>

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
<a name="troubleshoot-hardreboot-notification"></a>

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
<a name="troubleshoot-healthcheckfailure-notification"></a>

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
<a name="troubleshoot-availabilitymonitortest-notification"></a>

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
<a name="ha-health-notification-metrics"></a>

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.