Switch the protection mode

OceanBase Database provides three protection modes: maximum performance, maximum protection, and maximum availability. This topic describes how to switch between any two protection modes.

Background

Before you switch the protection mode, choose an appropriate target protection mode based on your requirements for performance, data protection, and cluster availability. For more information, see Protection mode overview

Procedure

1. In the primary cluster, run the following command to view its protection mode.

   obclient> SELECT CLUSTER_ROLE, PROTECTION_MODE FROM V$OB_CLUSTER;
   +----------------+--------------------------+
   | CLUSTER_ROLE | PROTECTION_MODE    |
   +----------------+--------------------------+
   |     PRIMARY      | MAXIMUM PERFORMANCE|
   +----------------+--------------------------+
   1 row in set
   

2. Properly configure log transmission parameters for different standby clusters based on their protection modes. For more information, see Log transfer service.

   The requirements for log transfer parameters vary with the protection mode:

   • Maximum performance mode: none.

   • Maximum protection mode: You can configure only one standby cluster in SYNC mode.

   • Maximum availability mode: you can configure only one standby cluster in SYNC mode. You can set the NET_TIMEOUT parameter for the standby cluster as required.

   In the primary cluster, run the following command to view the log transfer parameters of all standby clusters.

   obclient> SELECT CLUSTER_ID, REDO_TRANSPORT_OPTIONS FROM V$OB_STANDBY_STATUS;
   +-------------+-------------------------------------+
   | CLUSTER_ID | REDO_TRANSPORT_OPTIONS      |
   +-------------+-------------------------------------+
   |                  2 | SYNC NET_TIMEOUT = 30000000 |
   +-------------+-------------------------------------+
   1 row in set
   

3. Verify the cluster status to ensure successful switching.

   You can skip this step when you switch other modes to the maximum performance or maximum availability mode. However, when you switch other modes to the maximum protection mode, make sure that the following requirements are met:

   • The standby cluster in SYNC mode is synchronized with the primary cluster.

   • All servers in the primary cluster are active.

   If the requirements are not met, the switching will fail.

   To switch other modes to the maximum protection mode, perform the following operations:

   1. Log on to the primary cluster and query the SYNCHRONIZATION_STATUS field in the V$OB_STANDBY_STATUS view to learn of the synchronization status of the target standby cluster.

      obclient> SELECT CLUSTER_ID, SYNCHRONIZATION_STATUS FROM V$OB_STANDBY_STATUS;
      +-------------+---------------------------------+
      | CLUSTER_ID | SYNCHRONIZATION_STATUS |
      +-------------+---------------------------------+
      |                  2 |                        OK                     |
      +-------------+---------------------------------+
      1 row in set
      

      When SYNCHRONIZATION_STATUS is OK, the standby cluster is synchronized with the primary cluster. When SYNCHRONIZATION_STATUS is another value, the standby cluster is not synchronized with the primary cluster, and you need to identify the cause. For more information, see v$ob_standby_status.

   2. Log on to the primary cluster and query the __ALL_SERVER table to check whether all servers are active.

      obclient> SELECT COUNT(*) FROM __ALL_SERVER WHERE STATUS != 'ACTIVE';
      +----------+
      | COUNT(*) |
      +----------+
      |               0 |
      +----------+
      1 row in set
      

4. In the primary cluster, run the following command to switch its protection mode.

   obclient> ALTER SYSTEM SET STANDBY CLUSTER TO MAXIMIZE {AVAILABILITY | PERFORMANCE | PROTECTION};
   

5. Query the protection mode and protection level of each cluster to verify the switching result.

   For more information, see Protection mode and protection level.

   obclient> SELECT PROTECTION_MODE, PROTECTION_LEVEL FROM V$OB_CLUSTER;
   +---------------------------+----------------------------+
   |     PROTECTION_MODE    |       PROTECTION_LEVEL   |
   +---------------------------+----------------------------+
   | MAXIMUM PROTECTION | MAXIMUM PROTECTION |
   +---------------------------+----------------------------+
   1 row in set