Understanding CloudWatch alarms

CloudWatch alarms monitor information about your gateway based on metrics and expressions. You can add CloudWatch alarms for your gateway and view their statuses in the Storage Gateway console. For more information about the metrics that are used to monitor FSx File Gateway, see Understanding gateway metrics and Understanding file system metrics. For each alarm, you specify conditions that will activate its ALARM state. Alarm status indicators in the Storage Gateway console turn red when in the ALARM state, making it easier for you to monitor status proactively. You can configure alarms to invoke actions automatically based on sustained changes in state. For more information about CloudWatch alarms, see Using Amazon CloudWatch alarms in the Amazon CloudWatch User Guide.

Note

If you don't have permission to view CloudWatch, you can't view the alarms.

For each activated gateway, we recommend that you create the following CloudWatch alarms:

• High IO wait: IoWaitpercent >= 20 for 3 datapoints in 15 minutes

• Cache percent dirty: CachePercentDirty > 80 for 4 datapoints within 20 minutes

• Files failing upload: FilesFailingUpload >= 1 for 1 datapoint within 5 minutes

• File system error: FileSystem-ERROR >= 1 for 1 datapoint within 5 minutes

• Health notifications: HealthNotifications >= 1 for 1 datapoints within 5 minutes. When configuring this alarm, set Missing data treatment to notBreaching.

  Note

  You can set a health notification alarm only if the gateway had a previous health notification in CloudWatch.

For gateways on VMware host platforms that are part of a VMware High Availability cluster, we also recommend this additional CloudWatch alarm:

• Availability notifications: AvailabilityNotifications >= 1 for 1 datapoints within 5 minutes. When configuring this alarm, set Missing data treatment to notBreaching.

The following table describes CloudWatch alarm states.

State	Description
OK	The metric or expression is within the defined threshold.
Alarm	The metric or expression is outside of the defined threshold.
Insufficient data	The alarm has just started, the metric is not available, or not enough data is available for the metric to determine the alarm state.
None	No alarms are created for the gateway. To create a new alarm, see Create a custom CloudWatch alarm for your gateway.
Unavailable	The state of the alarm is unknown. Choose Unavailable to view error information in the Monitoring tab.