server_permanent_offline_time

Description

server_permanent_offline_time specifies the threshold for the heartbeat interruption time of a node. When the heartbeat of a node is interrupted for a duration exceeding this threshold, the node is considered permanently offline. For permanently offline nodes, the Root Service processes the data replicas on the OBServer node by removing them from the Paxos member group and replicating them to other available OBServer nodes to ensure the integrity of the Paxos member group.

Privilege requirements

• Query the parameter

  The sys tenant and all user tenants can query this parameter by using the SHOW PARAMETERS statement or the GV$OB_PARAMETERS view.

• Modify the parameter

  Only the sys tenant can modify this parameter. User tenants cannot modify this parameter.

Attributes

Considerations

By setting this parameter, you can avoid unnecessary replica replication. The system only initiates replica replication for permanently offline nodes when the replicas are lost for a duration exceeding the threshold.

The applicable scenarios and recommended values for this parameter are as follows:

• Database version upgrade: We recommend that you set this parameter to 72h.

  Note

  When you use OCP V2.3.5 or later to upgrade OceanBase Database V2.1.2 or later, the system automatically sets this parameter to 72h.

• Hardware replacement of OBServer nodes: We recommend that you set this parameter to 4h.

• Clearing and online activation of OBServer nodes: We recommend that you set this parameter to 10m to enable the cluster to go online quickly.

Examples

Set the threshold for the heartbeat interruption time of a node to 3600s.

obclient> ALTER SYSTEM SET server_permanent_offline_time = '3600s';

References

For more information about the Root Service, see Database-layer high availability.