Remove the arbitration service for a cluster

If you no longer need the arbitration service or the arbitration service fails, you can remove it from the cluster.

Prerequisites

The arbitration service is disabled for all tenants, including the sys tenant. Otherwise, an error occurs when you remove the arbitration service. For more information, see Disable the arbitration service.

Procedure

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

   Note that you must specify the corresponding fields in the following sample code based on your actual database configurations.

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

   For more information about how to connect to a database, see Overview (MySQL mode) or Overview (Oracle mode).

2. Execute the following statement to remove the arbitration service:

   ALTER SYSTEM REMOVE ARBITRATION SERVICE 'arb_server_ip:arb_server_port';
   

   The parameters are described as follows:

   • arb_server_ip: the IP address of the server from which the arbitration service is removed.

   • arb_server_port: the remote procedure call (RPC) port for the arbitration service to be removed. By default, Port 2882 is used.

   For example:

   ALTER SYSTEM REMOVE ARBITRATION SERVICE 'xx.xx.xx.192:2882';
   

   If the arbitration service works properly before the removal, the system automatically clears residual cluster information on the original OBServer node where the arbitration service resides. If the arbitration service fails before the removal, the system displays a warning, which indicates that the original OBServer node where the arbitration service resides contains residual cluster information. You can manually clear the residual cluster information by using the ob_admin tool. For more information, see Clear residual cluster information.

   Execute the following statement to view the warning:

   SHOW WARNINGS;
   

   The query result is as follows:

   +---------+-------+--------------------------------------------------------------------------------------------------------------------------+
   | Level   | Code  | Message                                                                                                                  |
   +---------+-------+--------------------------------------------------------------------------------------------------------------------------+
   | Warning | 4757  | Cluster info may remain on arbitration server 'xx.xx.xx.192:2882', please make sure whether to use ob_admin to clean it. |
   +---------+-------+--------------------------------------------------------------------------------------------------------------------------+
   1 rows in set
   

3. (Optional) Query the removal history of the arbitration service from the specified module in the DBA_OB_ROOTSERVICE_EVENT_HISTORY view.

   The syntax is as follows:

   SELECT * FROM oceanbase.DBA_OB_ROOTSERVICE_EVENT_HISTORY WHERE module LIKE "%arb_service%";
   

   The query result is as follows:

   +----------------------------+-------------+-----------------------------------+-------+--------+-------+--------------------------------------------------------------------------------------------------+-------+--------+-------+--------+-------+--------+-------+--------+------------+----------------+-------------+
   | TIMESTAMP                  | MODULE      | EVENT                             | NAME1 | VALUE1 | NAME2 | VALUE2                                                                                           | NAME3 | VALUE3 | NAME4 | VALUE4 | NAME5 | VALUE5 | NAME6 | VALUE6 | EXTRA_INFO | RS_SVR_IP      | RS_SVR_PORT |
   +----------------------------+-------------+-----------------------------------+-------+--------+-------+--------------------------------------------------------------------------------------------------+-------+--------+-------+--------+-------+--------+-------+--------+------------+----------------+-------------+
   | 2023-06-26 19:30:19.245664 | arb_service | admin_add_arbitration_service     | ret   | 0      | arg   | {arbitration_service_:"xx.xx.xx.192:2882"}                                                       |       |        |       |        |       |        |       |        |            | xx.xx.xx.194   |        2882 |
   | 2023-06-30 09:42:35.623655 | arb_service | admin_replace_arbitration_service | ret   | 0      | arg   | {arbitration_service_:"xx.xx.xx.64:2882", previous_arbitration_service_:"xx.xx.xx.192:2882"}     |       |        |       |        |       |        |       |        |            | xx.xx.xx.194   |        2882 |
   | 2023-06-30 09:51:09.756970 | arb_service | admin_remove_arbitration_service  | ret   | -4179  | arg   | {arbitration_service_:"xx.xx.xx.192:2882"}                                                       |       |        |       |        |       |        |       |        |            | xx.xx.xx.194   |        2882 |
   | 2023-06-30 10:10:48.858650 | arb_service | admin_replace_arbitration_service | ret   | 0      | arg   | {arbitration_service_:"xx.xx.xx.192:2882", previous_arbitration_service_:"172.30.140.64:2882"}   |       |        |       |        |       |        |       |        |            | xx.xx.xx.194   |        2882 |
   | 2023-06-30 10:42:32.688523 | arb_service | admin_remove_arbitration_service  | ret   | -4179  | arg   | {arbitration_service_:"xx.xx.xx.192:2882"}                                                       |       |        |       |        |       |        |       |        |            | xx.xx.xx.194   |        2882 |
   | 2023-06-30 10:43:41.913339 | arb_service | admin_remove_arbitration_service  | ret   | -4179  | arg   | {arbitration_service_:"xx.xx.xx.192:2882"}                                                       |       |        |       |        |       |        |       |        |            | xx.xx.xx.194   |        2882 |
   | 2023-06-30 10:44:05.616094 | arb_service | admin_remove_arbitration_service  | ret   | 0      | arg   | {arbitration_service_:"xx.xx.xx.192:2882"}                                                       |       |        |       |        |       |        |       |        |            | xx.xx.xx.194   |        2882 |
   +----------------------------+-------------+-----------------------------------+-------+--------+-------+--------------------------------------------------------------------------------------------------+-------+--------+-------+--------+-------+--------+-------+--------+------------+----------------+-------------+
   7 rows in set
   

What to do next

If you want to use the arbitration service after you remove it, you must redeploy the arbitration service. For more information, see Deploy an OceanBase cluster with two replicas and the arbitration service.

References

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

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

• Overview

• Enable the arbitration service for a tenant

• Disable the arbitration service for a tenant

• Modify the log stream downgrade control time

• Replace the arbitration service for a cluster

• Clear residual cluster information