server_permanent_offline_time

Description

server_permanent_offline_time specifies the threshold for the time when a node is considered permanently offline. When a node is permanently offline, the Root Service processes the data replicas on that node, removes them from the Paxos group, and replicates the data to other available OBServer nodes to ensure the integrity of the Paxos 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 starts the replication of data replicas on permanently offline nodes when the replicas are lost for a period longer than the specified threshold.

The applicable scenarios and recommended values of 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 an OBServer node: We recommend that you set this parameter to 4h.

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

Examples

Set the threshold for the time when a node is considered permanently offline to 3600s.

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

References

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