Enable arbitration service for a tenant

You can enable the arbitration service for a tenant when you create the tenant. For more information, see Create a tenant. If the arbitration service is not enabled for the tenant, you can enable it after the tenant is created. This topic describes how to enable the arbitration service for an existing tenant.

Prerequisites

• Make sure that the arbitration service is deployed in the current cluster. For more information, see Deploy an OceanBase cluster with two replicas and the arbitration service.

• Before you enable the arbitration service, make sure that the Locality of the tenant to be enabled is 2F or 4F. Currently, only tenants with a Locality of 2F or 4F can enable the arbitration service.

  Note

  Enabling the arbitration service only requires that the number of F replicas in the Locality of the tenant meets the requirements. The number of R replicas in the Locality of the tenant is not limited. For example, the arbitration service can be enabled for a tenant whose Locality is F@z1,F@z2 or F@z1,F@z2,R@z3.

Procedure

1. Log in to the sys tenant of the cluster as the root user.

   Here is an example of connecting to the database. Please replace the placeholders with the actual values in your environment.

   obclient -h10.xx.xx.xx -P2883 -uroot@sys#obdemo -p***** -A
   

   For more information about how to connect to the database, see Overview of database connection methods (MySQL mode) and Overview of database connection methods (Oracle mode).

2. Execute the following command to view the communication status of each node in the cluster.

   SELECT * FROM oceanbase.GV$OB_ARBITRATION_SERVICE_STATUS;
   

   The query result is as follows.

   +----------------+----------+-----------------------------+----------+
   | SVR_IP         | SVR_PORT | ARBITRATION_SERVICE_ADDRESS | STATUS   |
   +----------------+----------+-----------------------------+----------+
   | xx.xx.xx.197   |     2882 | xx.xx.xx.192:2882           | ACTIVE   |
   | xx.xx.xx.194   |     2882 | xx.xx.xx.192:2882           | ACTIVE   |
   +----------------+----------+-----------------------------+----------+
   2 rows in set
   

   Based on the value of the STATUS field in the query result, you can determine the communication status between each node and the arbitration service:

   • ACTIVE: The arbitration service communicates normally with the node. You can enable the arbitration service for the tenant only when all nodes communicate normally with the arbitration service.
   • INACTIVE: The arbitration service cannot communicate with the node. You cannot enable the arbitration service for the tenant. You need to check the network communication between the node and the arbitration service.

3. Execute the following command to view the arbitration service status of the tenant.

   SELECT * FROM oceanbase.DBA_OB_TENANTS WHERE tenant_name = 'oracle001'\G
   

   The query result is as follows.

   *************************** 1. row ***************************
                    TENANT_ID: 1004
                  TENANT_NAME: oracle001
                  TENANT_TYPE: USER
                  CREATE_TIME: 2025-06-26 19:40:21.457857
                  MODIFY_TIME: 2025-06-27 13:51:47.053502
                 PRIMARY_ZONE: zone1;zone2
                     LOCALITY: FULL{1}@zone1, FULL{1}@zone2
            PREVIOUS_LOCALITY: NULL
           COMPATIBILITY_MODE: ORACLE
                       STATUS: NORMAL
                IN_RECYCLEBIN: NO
                       LOCKED: NO
                  TENANT_ROLE: PRIMARY
            SWITCHOVER_STATUS: NORMAL
             SWITCHOVER_EPOCH: 0
                     SYNC_SCN: 1687845116605766616
               REPLAYABLE_SCN: 1687845116605766616
                 READABLE_SCN: 1687845116605766616
           RECOVERY_UNTIL_SCN: 4611686018427387903
                     LOG_MODE: NOARCHIVELOG
   ARBITRATION_SERVICE_STATUS: DISABLED
                     UNIT_NUM: 1
                   COMPATIBLE: 4.3.5.0
                    MAX_LS_ID: 1002
            RESTORE_DATA_MODE: NORMAL
                      COMMENT:
   1 row in set
   

   The arbitration service of the tenant can be in one of the following states:

   • ENABLED: The arbitration service is enabled for the tenant.

   • DISABLED: The arbitration service is disabled for the tenant.

   • ENABLING: The arbitration service is being enabled for the tenant.

   • DISABLING: The arbitration service is being disabled for the tenant.

   Based on the query result, the ARBITRATION_SERVICE_STATUS column is DISABLED, which indicates that the arbitration service is disabled for the tenant.

   For more information about the DBA_OB_TENANTS view, see DBA_OB_TENANTS.

4. Execute the following command to enable the arbitration service for the tenant.

   The statement is as follows:

   ALTER TENANT tenant_name [SET] ENABLE_ARBITRATION_SERVICE = true;
   

   In this statement, tenant_name specifies the name of the tenant for which you want to enable the arbitration service, and SET is an optional keyword.

   Here is an example of enabling the arbitration service for the oracle001 tenant:

   ALTER TENANT oracle001 ENABLE_ARBITRATION_SERVICE = true;
   

5. After the command is executed successfully, query the DBA_OB_TENANTS view again to confirm whether the arbitration service is enabled for the tenant.

   SELECT * FROM oceanbase.DBA_OB_TENANTS WHERE tenant_name = 'oracle001'\G
   

   The query result is as follows.

   *************************** 1. row ***************************
                    TENANT_ID: 1004
                  TENANT_NAME: oracle001
                  TENANT_TYPE: USER
                  CREATE_TIME: 2025-06-26 19:40:21.457857
                  MODIFY_TIME: 2025-06-27 13:54:29.486203
                 PRIMARY_ZONE: zone1;zone2
                     LOCALITY: FULL{1}@zone1, FULL{1}@zone2
            PREVIOUS_LOCALITY: NULL
           COMPATIBILITY_MODE: ORACLE
                       STATUS: NORMAL
                IN_RECYCLEBIN: NO
                       LOCKED: NO
                  TENANT_ROLE: PRIMARY
            SWITCHOVER_STATUS: NORMAL
             SWITCHOVER_EPOCH: 0
                     SYNC_SCN: 1687845307275557916
               REPLAYABLE_SCN: 1687845307275557916
                 READABLE_SCN: 1687845307131393135
           RECOVERY_UNTIL_SCN: 4611686018427387903
                     LOG_MODE: NOARCHIVELOG
   ARBITRATION_SERVICE_STATUS: ENABLED
                     UNIT_NUM: 1
                   COMPATIBLE: 4.3.5.0
                    MAX_LS_ID: 1002
            RESTORE_DATA_MODE: NORMAL
                      COMMENT:
   1 row in set
   

   Based on the query result, the ARBITRATION_SERVICE_STATUS column is ENABLED, which indicates that the arbitration service is enabled for the tenant.

6. After the arbitration service is enabled for the tenant, the tenant may still have log streams that lack arbitration members. These log streams cannot be upgraded or downgraded normally. You can follow the steps below to confirm this.

   Enabling the arbitration service for the tenant indicates that all log streams created at the time of enabling the arbitration service can use the arbitration service. However, new log streams created after the arbitration service is enabled may lack arbitration members. This is because log streams are created in non-strict mode, and the creation of arbitration members is not guaranteed. Therefore, you can use the following statement to confirm whether all log streams of the tenant have arbitration members.

   The statement is as follows:

   (SELECT distinct ls_id FROM GV$OB_LOG_STAT WHERE tenant_id = tenantid) EXCEPT
   (SELECT ls_id FROM GV$OB_LOG_STAT WHERE tenant_id = tenantid AND role = 'LEADER' AND arbitration_member = 'arb_server_ip:arb_server_port');
   

   The parameters are described as follows:

   • tenantid: the tenant ID of the tenant for which the arbitration service is enabled.

   • arb_server_ip: the IP address of the arbitration service.

   • arb_server_port: the RPC port of the arbitration service. The default value is 2882.

   Here is an example:

   (SELECT distinct ls_id FROM GV$OB_LOG_STAT WHERE tenant_id = 1004) EXCEPT
   (SELECT ls_id FROM GV$OB_LOG_STAT where tenant_id = 1004 and role = 'LEADER' and arbitration_member = '100.xx.xx.xx:2882');
   

   If the query result is empty, all log streams have arbitration members, and the arbitration service is available. If the query result is not empty, the Root Service will automatically add arbitration members to these log streams in the background. You can query the CDB_OB_LS_ARB_REPLICA_TASKS view to confirm whether there are ongoing tasks to add arbitration members. If such tasks exist and are ongoing, you need to wait for them to complete.

   After the tasks to add arbitration members are completed, you can query the CDB_OB_LS_ARB_REPLICA_TASK_HISTORY view to confirm the task results. If the tasks are successful, the log streams have arbitration members, and the arbitration service is available. If the tasks fail, contact OceanBase support for assistance.

   For more information about the fields of the GV$OB_LOG_STAT view, see GV$OB_LOG_STAT.

References

For more information about arbitration service, see the following topics:

• Deploy an OceanBase cluster with two replicas and the arbitration service

• Disable the arbitration service for a tenant

• Modify the degradation timeout

• Replace the arbitration service for a cluster

• Delete the arbitration service for a cluster