DDM Monitoring

Introduction

A DDM monitor detects your database status, and automatically triggers traffic switching when the database is abnormal.

Prerequisites

• A multi-active instance and the corresponding function module have been created.
• A database instance to be monitored has been created in the data center. The monitored database and connected database have been created.
  • Monitored Database: two databases with the same name exist in both data centers. Use a monitored database that is different from your service database.
  • Connected Database: two databases with the same name exist in both data centers.

Creating a DDM Monitor

1. Log in to the MAS console. On the Multi-Active Instances page, click an instance whose namespace type is Intra-city multi-active.
2. Click the Monitor List tab and click Create Monitor.
3. Configure the basic information, then click Next: Data Centers.
   Figure 1 Basic information configurations
   

   Table 2 Basic information parameters

   Parameter	Description
   Monitor	Select DDM Monitoring.
   Application	Select an application.
   Monitor Name	Customize the monitor name.
   Exception Notification	By default, this option is disabled. If it is enabled, monitor and database exceptions will be sent to you in a timely manner. To enable this option, configure a secret key first. Cloud Eye is enabled by default. Ensure that the alarm rules for MAS have been created on the Cloud Eye console. For details, see Creating an Alarm Rule to Monitor an Event.
   Monitoring	The default value is Yes. If No, database exceptions will not be monitored.
   Automatic Switchover	The default value is Yes. If No, automatic switchover of the databases will not be triggered.
   Username	Enter the username for logging in to the database.
   Password	Enter the password for logging in to the database.

4. Configure the data centers, then click Next: Databases.
   Figure 2 Data center configurations
   

   Table 3 Data center parameters

   Parameter	Description
   Cloud	The environment where the monitored database is deployed
   Region	The region where the monitored database is located
   Connection Address	The IP address and port number for accessing the DDM database

5. Configure the databases, then click Next: Advanced.
   Figure 3 Database configurations
   

   Table 4 Database parameters

   Parameter	Description
   Monitored Database	Enter the monitored database name. It is used to detect availability and check whether the database instance connection is normal. To prevent risks, it is recommended to use a monitored database that is different from your service database and has been granted only the read permissions.
   Connected Database	Enter the connected database name. It is the database to which the application is actually connected. You can select different routing algorithms for them in the connection pool configuration.

6. Configure the advanced settings, then click Next: Confirm.
   Figure 4 Advanced configurations
   

   Table 5 Advanced settings

   Parameter	Description
   Retry Interval (ms)	The interval of reconnection attempts, in milliseconds. Default value (recommended): 3000 Value range: 1000 to 300000
   Monitoring Timeout (ms)	The timeout duration before a monitor becomes abnormal, in milliseconds. Default value: 20000 (in milliseconds). Value range: 12000 to 1200000 NOTE: Ensure that the time you specify here is longer than the time required for data center 1 to synchronize data to data center 2. Otherwise, the data in data center 2 may be incomplete.
   Database Access Timeout (ms)	The database access timeout duration, over which the database access is considered failed, in milliseconds. Default value (recommended): 3000 Value range: 3000 to 100000

7. Confirm settings and click Create.
   

   If the created monitor is not normal, that is, its indicator is not green, its configurations or databases may be abnormal. In this case, rectify the fault.