Monitor the disk usage

This topic describes how to use CloudMonitor to configure alert rules on the disk usage of a cluster in the reserved mode. For example, you can configure the following alert rule: If the disk usage is equal to or greater than 90%, AnalyticDB for MySQL blocks data write requests and processes data read requests only.

1. Log on to the AnalyticDB for MySQL console.
2. In the upper-left corner of the page, select the region where the cluster you want to manage resides.
3. In the left-side navigation pane, click Clusters.
4. On the V3.0 Clusters tab, click the Cluster ID.
5. In the left-side navigation pane, click Monitoring Information.
6. On the Monitoring Information page, click Alert Rule Settings. The CloudMonitor console appears.

   On the Monitoring Information page, you can click the Cluster Monitor or Table Monitor tab to view the monitoring information about the cluster.

   In the reserved mode, the disk usage is displayed as a percentage. In the elastic mode where disk monitoring is not required, the used disk space is displayed.

   • Reserved mode
     Note The maximum disk usage indicates the highest disk usage among all nodes in the cluster. If the value is equal to or greater than 90%, the disk is locked. We recommend that you pay special attention to this metric.
   • Elastic mode
     Note In the elastic mode, data is stored in hard disk drives (HDDs) and HDDs are automatically scaled out. This prevents HDDs from being locked due to insufficient storage capacity. The Cluster Monitor tab displays the actual amount of stored data. Therefore, you do not need to configure alert rules to monitor the disk usage in the elastic mode.
7. On the Threshold Value Alarm tab of the Alarm Rules page, click Create Alarm Rule.
8. On the Create Alarm Rule page, configure the following parameters.

   Parameter	Description
   Product	The name of the service for which you want to set the alert rule. Select AnalyticDB for mysql 3.0.
   Resource Range	The resources to which the alert rule applies. You can select Cluster or All Resources. All Resources: The alert rule applies to all your instances of the specified service. Assume that you set Resource Range to All Resources for a rule that triggers an alert if the disk usage of an AnalyticDB for MySQL V3.0 cluster is equal to or greater than 90%. This alert rule applies to all AnalyticDB for MySQL V3.0 clusters under your account. Each alert rule applies to a maximum of 1,000 resources of the specified service. If more than 1,000 resources of the specified service are created under your account, the system may not generate an alert when the rule conditions are met. We recommend that you classify resources of the same service into different application groups based on your business requirements before you set the alert rule. Cluster: The alert rule applies to a specified cluster only. Assume that you set Resource Range to Cluster for a rule that triggers an alert if the disk usage of a cluster is equal to or greater than 90%. An alert is triggered only if the disk usage of the specified cluster is equal to or greater than 90%.
   Alarm Rule	Enter the name of the alert rule.
   Rule Description	Enter the content of the alert rule. This parameter defines the alert trigger conditions. Assume that you define a rule that triggers alerts if the average disk usage in the last 5 minutes is greater than or equal to 90%. The system checks whether the trigger condition is met once every 5 minutes.
   Mute for	Set the period during which an alert is muted. This parameter specifies the interval at which an alert notification is sent to the specified contacts if the alert is not cleared.
   Effective Period	Set the period during which the alert rule is effective. The system monitors the metrics and generates alerts only if the alert rule is effective.
   Notification Contact	Specify the contact groups to which alert notifications are sent.
   Notification Methods	Email + DingTalk (Info)
   Email Remark	Enter the additional information that you want to include in the alert notification email.
   HTTP CallBack	Enter a URL that can be accessed from the Internet. CloudMonitor uses a POST request to send an alert notification to this URL. Only the HTTP protocol is supported.

9. After you configure the preceding parameters, click Confirm.