Oracle Cloud Infrastructure Documentation

Enabling or Disabling High Availability

Enabling high availability converts a standalone DB system to a high availability DB system and disabling high availability converts a high availability DB system to a standalone DB system.

  • Enabling high availability on a standalone DB system creates a highly available DB system using the existing MySQL instance as the primary instance, creating two more secondary instances, and replicating the data present in the primary instance to the secondary instances. No downtime occurs.
  • Disabling high availability on a DB system creates a standalone DB system from the instance running in the preferred primary placement.
    • If the primary instance is running in the preferred primary placement, no downtime occurs.
    • If the primary instance is not running in the preferred primary placement, a failover occurs and this causes a short downtime.

Using the Console

Use the Console to enable or disable high availability on a standalone DB system.

This task requires the following:
  • A running standalone DB system.
  • Primary keys exist on every table in the database. See Prerequisites.
  • Any active inbound replication channel on the DB system must be stopped for the duration of this task. See Enabling or Disabling a Channel. You cannot enable high availability while an active channel is connected to the DB system. This is required only if the configuration used by the DB system is not compatible with high availability. If the DB system is using a compatible configuration, it is not necessary to stop the inbound replication channel to enable high availaibility. Changing the configuration of a DB system requires a restart of the DB system.
  • Crash recovery is enabled. You cannot enable high availability on a DB system if crash recovery is disabled. See Crash Recovery.
  • MySQL version must be 8.0.24 or higher. You cannot enable high availability on earlier versions of MySQL. If the DB system uses a version older than 8.0.24, you must upgrade before enabling high availability.
  • If you intend to configure an inbound replication channel on this DB system, you must import data before enabling high availability, and configure your channel after high availability is enabled.
Note

If you encounter OutOfHostCapacity work request error while enabling high availability in a DB system, see Resolving OutOfHostCapacity Error.
Note

If a HeatWave cluster load or reload operation is going on, enabling or disabling high availability can fail. It is recommended to not enable or disable high availability while a HeatWave cluster load or reload operation is going on.
  1. To enable high availability on a DB system, do the following:
    1. Open the Enable high availability dialog box from one of the following locations:
      • The Enable high availability menu item from the Actions menu on the DB Systems list page.
      • The Enable high availability menu item from the Actions menu on the DB System Details page.
      • The Enable link adjacent the High availability label on the DB System Details page.
    2. In the Enable high availability dialog box, click Enable.
    3. (Optional) If the DB system is not using a high availability-compatible configuration, you must select one from the Configuration drop-down list, and then click Enable.
    The DB system enters the UPDATING state. The secondary instances are cloned from the primary instance and a high availability DB system is formed. The process does not cause any downtime to the DB system. If the updating process fails, the DB system returns to a standalone state. Check the work request for details of the failure.
  2. To disable high availability on a DB system, do the following:
    1. Open the Disable high availability dialog box from one of the following locations:
      • The Disable high availability menu item from the Actions menu on the DB systems list page.
      • The Disable high availability menu item from the More Actions drop-down menu on the DB System Details page.
      • The Disable link adjacent the High availability label on the DB System Details page.
    2. In the Disable high availability dialog box, click Disable.
    The DB system enters the UPDATING state. If the primary instance is not located in the preferred primary placement, a controlled failover occurs and this causes a short downtime.

    The primary instance located in the preferred primary placement is converted to a standalone DB system and the two secondary instances are deleted. This process does not cause any downtime to the DB system.

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