OceanBase Database V4.1 and later provide the arbitration service, which consumes minimal resources and supports multiple clusters. You can use the arbitration service to deploy high-availability architectures based on OceanBase Database at lower costs. For example, you can deploy an architecture with two full-featured replicas and one arbitration service (2F1A) or a 4F1A architecture. These architectures help enterprises control the resource costs, ensure high availability of a database system, and greatly improve the cost effectiveness of the system.
However, a single arbitration service introduces the risk of single points of failure during the operation. If the arbitration service fails, the high availability of the associated OceanBase clusters will be downgraded until the failure is fixed. This may cause a negative impact on business continuity and stability.
In response to that issue, OceanBase Database allows you to create an arbitration service group. When an arbitration service node fails, the associated cluster can be switched to a healthy arbitration service node within seconds. This maximizes the stability of OceanBase clusters in various complex scenarios and ensures zero business interruptions.
What is an arbitration service group?
An arbitration service group contains multiple arbitration services. When OceanBase Cloud Platform (OCP) detects that an arbitration service fails, it automatically switches the associated clusters to another arbitration service in the group.
As shown in the preceding figure, an arbitration service group contains multiple arbitration services, and works based on a switching strategy.
Priorities of arbitration services
Arbitration services in an arbitration service group have a priority attribute. When the switching strategy is triggered for the associated OceanBase clusters, OCP switches the clusters to an arbitration service with a higher priority. If the resources of that arbitration service are insufficient, some OceanBase clusters are switched to an arbitration service of a lower priority.
Switching strategy
The switching strategy consists of a triggering condition and the duration of the exception.
Valid values of the triggering condition are as follows:
- Default: Half of the replicas of tenants in an OceanBase cluster cannot connect to the arbitration service.
- Number: The number of units in an OceanBase cluster that cannot connect to the arbitration service.
- Percentage: The percentage of units in an OceanBase cluster that cannot connect to the arbitration service.
Duration of the exception: This parameter specifies when to switch the arbitration service for an OceanBase cluster after the specified condition is triggered.
Prerequisites
To view the list of arbitration service groups, make sure that you have the following permissions:
- Resource permissions: Arbitration service read-only permission.
- Menu permissions: Permission on the Overview menu of clusters.
View the list of arbitration service groups
Log in to the OCP console. In the left-side navigation pane, click Clusters. On the page that appears, click the Service Group tab.
The list of arbitration service groups displays the following information of each arbitration service group: host, priority, service port, remarks, version, associated clusters, replacement condition upon exceptions, automatic execution, time of last modification, and status. You can search for an arbitration service by its host IP address or the name of an associated cluster.
You can click the IP address of a host to go to the host monitoring page. For more information, see View host performance data, View host resource monitoring data, and View host process monitoring data.
You can click the name of a cluster associated with an arbitration service to go to the Overview page of the cluster. For more information, see View the details of a cluster.
You can filter arbitration service groups by status.
Manage service groups
You can also upgrade, edit, and delete service groups. For more information, see Upgrade an arbitration service group, Edit an arbitration service group, and Delete an arbitration service group.