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Disaster Recovery Instance

Last updated: 2022-05-27 15:10:06

    Overview

    For applications with high requirements of service continuity, data reliability, and compliance, TencentDB for MySQL provides cross-region disaster recovery instances to help enhance your capability to deliver continued services at low costs and improve data reliability.

    Note:

    A disaster recovery instance costs the same as the source instance associated with it. For more information, see Product Pricing.

    Features

    • With a separate database connection address, a disaster recovery instance can offer read access capability for various scenarios such as nearby access and data analysis with lower costs of device redundancy.
    • Its highly available source/replica architecture helps avoid single points of failure for databases.
    • Data is synced over a private network with lower latency and higher stability compared to 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.

    How it works

    • If a TencentDB instance is used as a disaster recovery database, this instance will be the backup of the source instance.
    • When any change takes place in the source instance, the log information recording the change will be copied to the disaster recovery instance and then data sync will be implemented through log replay.
    • If any failure occurs in the source instance, the disaster recovery instance can be activated in seconds to provide full read/write capability.

    Feature Limits

    • Disaster recovery instances can be purchased only for high available GTID-enabled source instances on MySQL 5.6 or later with the InnoDB engine at a specification of 1 GB memory and 50 GB disk capacity or above. If your source instance is below this specification, upgrade it first.
      Note:

      If GTID is not enabled, you can enable it on the instance details page in the console. This operation takes a long time, and the instance will be disconnected for several seconds. We recommend you do so during off-peak hours and add a reconnection mechanism in the programs that access the database.

    • The minimum specification of a disaster recovery instance is 1 GB memory and 50 GB disk capacity and must be at least 1.1 times the storage capacity used by the source instance.
    • One source instance can have one disaster recovery instance at most. Even if the existing disaster recovery instance is in isolation, you cannot create new ones.
    • Disaster recovery instance does not support the following features: transferring project, rollback, SQL operation, changing character set, account management, changing port, data import, rollback log, and read-only instance.

    Directions

    Creating a disaster recovery instance

    Step 1. Create a disaster recovery instance

    1. Log in to the TencentDB for MySQL console. In the instance list, click an instance ID or Manage in the Operation column to access the details page.
    2. Make sure that the GTID feature is enabled by viewing the basic information of the instance on the Instance Details page. Click Add Disaster Recovery Instance in the instance architecture diagram to enter the disaster recovery instance purchase page.
    3. On the purchase page, set basic information of the disaster recovery instance such as Billing Mode, Region, and Sync Policy.
    • If the sync policy is Sync Now, data will be synced immediately when the disaster recovery instance is created.
    1. After confirming that everything is correct, click Buy Now and wait for disaster recovery instance delivery.
    2. Return to the instance list. After the status of the instance changes to Running, it can be used normally.

    Managing disaster recovery instances

    • View a disaster recovery instance
      A disaster recovery instance can be viewed from the region where it resides. You can use the instance list to filter out all instances in a specific region.

    • View the relationship
      Click the icon on the right of a disaster recovery instance or source instance to view their relationship.

    • View sync delay
      View the sync delay between the source instance and the disaster recovery instance at the top of the Instance Details page of the disaster recovery instance.

    • Disaster recovery instance features
      A disaster recovery instance has various features, such as instance details, instance monitoring, database management, security group, and backup and restoration.

    Promoting disaster recovery instance to source instance

    You can promote a disaster recovery instance to source instance in the console as needed.

    1. Log in to the TencentDB for MySQL console, click the ID of the disaster recovery instance to be promoted in the instance list, and access the instance management page.
    2. Click Promote to Source Instance in the top-right corner to promote the disaster recovery instance to source instance. After the promotion, the sync link with the source instance will be disconnected, so that the promoted instance can get data write capability and full MySQL functionality.
      Note:

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

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