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Disaster Recovery Read-Only Instance

Last updated: 2022-04-25 16:47:26

    This document describes how to create and manage disaster recovery read-only instances in the console.


    TencentDB for MariaDB provides cross-AZ/region disaster recovery read-only instances to enhance your capacity to deliver continuous services at low costs while improving data reliability for applications with greater service continuity, data reliability, and compliance requirements.


    Disaster recovery read-only instance costs the same as the primary instance. For detailed pricing, see Pricing

    Use Cases

    • Remote disaster recovery: To ensure data security, you can use disaster recovery instances to back up your business and data in multiple regions. In the event that an instance becomes unavailable due to an AZ/region failure, you can quickly switch to a cross-AZ/region disaster recovery instance to minimize the impact on your business.
    • Nearby access: You can use an instance in a specific AZ as the primary instance and those in other AZs/regions as read-only instances, which provides users with nearby access, remote read capabilities, and improved access speed.
    • Multi-region deployment: MariaDB instance can be deployed across multiple regions. When an MariaDB instance experiences network fluctuations or unavailability in an AZ/region, it can be switched to another AZ/region based on business needs.


    • Disaster recovery read-only instances provide separate database connection addresses for read-only access. They can be used for nearby access and data analysis at a lower cost of device redundancy.
    • A primary instance can create multiple disaster recovery read-only instances that can be deployed in different regions and AZs.
    • Disaster recovery read-only instances support high-availability(1 primary-1 replica and 1 primary-2 replica) architecture, which helps avoid single point of failure for databases.
    • If the primary instance fails, the disaster recovery read-only instance can be activated in seconds to provide full read/write capability.
    • Data in a disaster recovery read-only instance is synced over a private network, which has lower latency and greater stability than a public network.
    • The traffic of data sync over a private network is currently free of charge during the promotion period. If fees will be charged for it, we will inform you in advance.

    Feature Limits

    • Disaster recovery read-only instance do not support parameter setting and account management features.
      Database version of disaster recovery read-only instance is the same as that of the primary instance by default. Instance specification and disk size should be greater than or equal to that of the primary instance.


    Create a disaster recovery read-only instance

    1. Log in to the MariaDB console, click an instance ID in the instance list, and enter the instance management page.
    2. In instance architecture diagram on the instance details page, click Add Disaster Recovery Read-Only Instance, and enter instance purchase page.
    3. On the purchase page, set billing mode, region, and other basic info of disaster recovery read-only instance, and click Buy Now.

      • The time required to complete the creation depends on the amount of data, and no operations can be performed on the primary instance in the console during the creation. It’s recommended to do so at an appropriate time.
      • Only the entire instance data can be synced. Make sure that the disk space is sufficient.
        Make sure that the primary instance is in the running status and no tasks are executing, otherwise the sync task may fail.
    4. Return to instance list after payment, initialize the instance, and you can proceed to the subsequent operations.

    Manage disaster recovery read-only instances

    • View disaster recovery read-only instances
      You can view disaster recovery read-only instances from the region where they reside, and filter them out in the instance list.
    • View the relationship between the primary instance and the disaster recover read-only instance
      In instance architecture diagram on the instance details page, you can view the relationship between the primary instance and the disaster recover read-only instance.
    • Disaster recovery read-only instance feature
      Disaster recovery read-only instance provides instance details, system monitoring, data security, backup and recovery, and performance optimization features.

    Promote a disaster recovery read-only instance to the primary instance

    You can promote a disaster recovery read-only instance to primary instance in the console as needed.

    1. Log in to the TencentDB for MariaDB console, select the target disaster recovery read-only instance, click an instance name in the instance list to enter the instance management page.
    2. Click Promote to Primary Instance in the top-right corner to promote the disaster recovery read-only instance to primary instance. After the promotion, the sync link with the primary instance will be disconnected, so that the promoted instance can get data write capability and full MariaDB functionality.

      The disconnected sync link cannot be reconnected. You must exercise caution with this operation.

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